Sentence:  At this stage (similar to pl. 2, figs. 6-7), the coiling becomes increasingly ventrally directed with the clear onset of Streptospirality, and the aperture, as it increases in height, becomes, in part, <WSD>pseudoumbilical</WSD> (i. e., its inner portion lies over a developing umbilical depression). 
Meaning of the word marked with <WSD> tags:  Having the appearance or some of the properties of a navel (umbilicus) or an umbilical cord.