Cephalaspidea in 1660–1661 Jan Vermeer painted a quite accurate portrait of the city Delft. Cities like Amsterdam, Haarlem and The Hague also became popular subjects for paintings. Painters from other European countries (i.e., Great Britain, France, Germany) followed the Dutch example. The 18th century was a flourishing period for cityscape painting in Venice (Canaletto, Guardi). At the end of the 19th century the impressionists focused on the atmosphere and dynamics of everyday life in the city. Suburban and industrial areas, building sites and railway yards also became subjects for cityscapes. During the 20th century attention became focused on abstract and conceptual 	Cityscape
7781376	art, and thus the production of cityscapes declined. American painter Edward Hopper, who stayed loyal to figurative painting, created intriguing images of the American scene. With a revival of figurative art at the end of the 20th century comes a revaluation of the cityscape. Well-known living cityscape painters are Rackstraw Downes, Antonio López García, and Richard Estes. American artist Yvonne Jacquette has made a specialty of aerial cityscapes. Cityscape In the visual arts, a cityscape (urban landscape) is an artistic representation, such as a painting, drawing, print or photograph, of the physical aspects of a city or urban area	Cityscape
7781377	Pyotr Frolov Pyotr Frolov Pyotr Kozmich Frolov (; – ) was a Russian mining engineer and inventor who built the first horse-railway in the Russian Empire in 1809. He elaborated on various canal projects and other artificial water constructions. Frolov also contributed to the development of scientific research and to the culture of the Altay region. His activities as a head of the Kolyvano-Voskresensk factories promoted a great advance of Russian technology in the beginning of the 20th century. Pyotr Frolov Pyotr Kozmich Frolov (; – ) was a Russian mining engineer and inventor who built the first horse-railway in the Russian Empire in 1809	Pyotr Frolov
7781378	Cephalaspidea Cephalaspidea The order Cephalaspidea, also known as the headshield slugs and bubble snails, is a major taxon of sea slugs and bubble snails, marine gastropod mollusks within the larger clade Euopisthobranchia. Bubble shells is another common name for these families of marine gastropods, some of which have thin bubble-like shells. This clade contains more than 600 species. Members of this worldwide clade used to be considered the most primitive of the opisthobranchs, but now they are considered as derived and specialized members of the Euthyneura Headshield slugs are the most morphologically diverse group of all the opisthobranchs. Anatomy. The 	Cephalaspidea
7781379	vast majority possess a shell, although it may be reduced or internal. They have a well-developed headshield, a characteristic broadening at the head, which is used to plow beneath the surface of the sand. This headshield prevents the sand entering the mantle cavity. There is a muscular foot with or without parapodia (fleshy wing-like flaps). Life habits and related anatomical structures. Headshield slugs often live just beneath the surface of the sand and can also be seen crawling on rocks. They have well-developed sensory structures to detect prey, which may be other opisthobranchs, polychaetes or bristleworms and 	Cephalaspidea
7781380	foraminiferans. Several species are voracious carnivores. Members of the brightly colored genus Chelidonura" also have well-developed eyes on the anterior end of the head and bundles of sensory cilia around the mouth. With these cilia they are able to track their prey by following the victim’s mucous trail. The Hancock's organ is a chemosensory organ situated between the foot and the headshield. It plays a role in olfactory and sensory detection. It is visible as a dark brown pit at the base of the right rhinophore. Taxonomy. The taxonomy of the shelled cephalaspideans, the bubble snails, like  that of many shelled mollusks, used to be based very simply on shell characteristics. But because there are some similarities in shell morphology throughout this group, more recently taxonomists have taken other anatomical characteristics into consideration, such as the radula, gizzard, penis, and Hancock’s organ. In 2015 a new study based on molecular phylogenetics has changed significantly the taxonomy of the Cephalaspidea. The monophyly of the Cephalaspidea was confirmed, but the families Cylichnidae, Diaphanidae, Haminoeidae, Philinidae, and Retusidae were found non-monophyletic. This had led to the creation of new families ((Alacuppidae, Colinatydidae, Colpodaspididae, Mnestiidae, Philinorbidae) ) and one new  genus ("Alacuppa"). Two family names (Acteocinidae, Laonidae) and two genera ("Laona", "Philinorbis") are reinstated as valid 2005 taxonomy. In the taxonomy of Bouchet & Rocroi (2005), the clade Cephalaspidea is arranged as follows: The superfamily Acteonoidea has been included into the new Informal Group "Lower Heterobranchia" and the superfamily Cylindrobulloidea becomes part of the Group Cylindrobullida. 2009 taxonomy. Malaquias et al. (2009) have rearranged taxonomy of Cephalaspidea "sensu lato": The taxonomy of Cephalaspidea "sensu lato" by Malaquias et al. (2009) is arranged as follows (there are listed genera under molecular analysis; not analyzed families are under "incertae sedis"): Architectibranchia Haszprunar, 1985  Runcinacea Burn, 1963 Cephalaspidea Fischer, 1887 - This means Cephalaspidea "sensu stricto" 2010 taxonomy. Subsequently Malaquias (2010) moved "Bullacta exarata" (formerly the only member of Bullactidae) into the family Haminoeidae. Jörger et al. (2010) moved Cephalaspidea "sensu stricto" and Runcinacea into the Euopisthobranchia and they confirmed the placement of Acteonoidea within the Lower Heterobranchia. All families of Architectibranchia were already within the Lower Heterobranchia in the taxonomy of Bouchet & Rocroi, except for the Notodiaphanidae, which has been placed in the Lower Heterobranchia since 2010, in order that the Architectibranchia can be considered to be monophyletic. 2015 taxonomy. The publication by Oskars  T.R., Bouchet P. & Malaquias M.A. (2015)". A new phylogeny of the Cephalaspidea (Gastropoda: Heterobranchia) based on expanded taxon sampling and gene markers." in the journal Molecular Phylogenetics and Evolution. 89 came to the following conclusion, with the creation of new families The superfamily Bulloidea was not supported in the Bayesian phylogenetic hypothesis and Diaphanoidea was found polyphyletic. The superfamilies Haminoeoidea and Philinoidea were accepted. The composition of each of the superfamilies was drastically rearranged. Cephalaspidea The order Cephalaspidea, also known as the headshield slugs and bubble snails, is a major taxon of sea slugs and bubble snails, marine gastropod mollusks