92 ANCILLARTA. 



(Jen us ANCILLARIA, Lain. 



The animal of Ancillaria is voluminous, covering the entire 

 shell with the exception of the spire. The head, which is 

 entirely concealed by the reflected portions of the foot, consists 

 of a short cylindrical, inflated, annulated proboscis, above which 

 is a semilunar veil formed by the dilatation and union of the 

 tentacles ; there is no indication of eyes. The mantle is pro- 

 duced anteriorly into a long siphon. The foot is large and 

 bursiform, the side-edges being greatly extended and reflected 

 over the shell, meeting in the middle on the back. As in Oliva, 

 it is deeply fissured anteriorly, forming & semilunar disk before 

 the head, divided by a deep longitudinal groove into two lateral, 

 triangular lobes, acuminated transversely ; posteriorly it is 

 bilobed, and is either without an operculum, or is provided with 

 a thin, horny unguiform one, with apical nucleus, semilunar 

 growth-lines, and an oval muscular impression. 



The Ancillarise resemble the Olives in their habits, dwelling 

 among the smooth sands in which they frequently bury them- 

 selves. They crawl with a quick, sliding motion, and as they 

 glide briskly along, the shell is enveloped in the alar expansions 

 of the foot, which overlap each other slightly in the middle, and 

 extending considerably beyond the spire, form posteriorly a 

 loose, open sack ; anterior to these lobes the tubular cylindrical 

 siphon is visible, directed upwards and backwards, and even 

 laid flat upon the back. 



The Ancillarise have been monographed by Sowerby in the 

 Thesaurus Conchyliorum, by Reeve in Conchologia Iconica, 

 and by Weinkauff in Kiister's Conchylien Cabinet. The last 

 authority enumerates forty-six species, some of which he con- 

 siders doubtful. A very careful consideration of these forms 

 has induced me to reduce the number of species considerably. 

 They are tropical animals, the t}'pical group inhabiting the Red 

 Sea, Indian Ocean, Australia, Japan, etc. ; one species only 

 occurring in American waters, in the Caribbean province. The 

 earliest fossils are from the eocene strata of the United States 

 and Europe ; they are few in number, and the genus, never 

 numerous in species, appears to have reached its maximum 

 development at the present time. 



Ancillaria is, through Olivancellaria, very closely connected 



