REPOKT UN THE Tl NICATA. 129 



and more numerous papillae. In the small piece of test examined, no vessels were to be 

 seen. The mantle, like that of the smaller species of Culeolus, is thin, and the muscula- 

 ture is feeble but distinct. 



The must striking point of resemblance, however, is in the structure of the branchial 

 sac (PL XIII. fig. 9). That organ lias here the same simple type hitherto found only 

 in Culeolus, and in Bathyoncus, one of the Styelime. The sac is especially like that of 

 Culeolus perlueidus, from which it differs chiefly in that there the fold is formed of 

 simply two internal longitudinal bars, while in the present species there are always three 

 ( PI. XIII. fig. 9, or.f.) I have no1 been able to detect calcareous spicules in any part of the 

 sac. Cilia are present on the internal longitudinal bars, but seem to be confined to the sides, 

 being placed on the small cubical cells forming the lateral walls of the vessel, while 

 the columnar cells outhe free internal edge have none. 



<r.a. 



Fig. 16. — Diagrammatic lateral view of Fungvhu cinereus, showing the course of the Alimentary Canal. 

 Br., branchial aperture ; At., atrial aperture ; pal., peduncle ; br.s., branchial sac ; ce.a., oesophageal aperture ; >'., intestine ; 



a., anus ; g., genital gland of left side. 



I could discover no languets. A plain band, about twice the breadth of an internal 

 longitudinal bar, runs along the dorsal edge of the branchial sac, and appears to represent 

 the dorsal lamina, The endostyle is very distinct, but has no calcareous spicules. The 

 central area is about one-third of the entire breadth (PI. XIII. fig. 10), and is traversed 

 by three pairs of opaque brown bands (c.b.a., and l.b.h.) running longitudinally. One 

 ■ >f the prominent edges in the piece examined has the blood vessels engorged with brown 



I'l 1 corpuscles (PI. XIII. fig. 10, cap.), while the other edge is clear and transparent. 



The tentacles are large and much branched. The exact number could not be made out, 

 but it is probably about eight. 



The alimentary canal is undifferentiated into regions, and hangs freely in the peri- 

 branchial space, having no attachment (except by blood vessels) to the mantle. The 

 oesophageal aperture lies at the posterior end of the branchial sac (fig. 16, ce.a.), and 

 the tube has the following course It first runs ventrally and then anteriorly along the 

 ventral side of the branchial sac. It next turns dorsally ('•) and posteriorly and then 

 ventrally, so as to form a curve convex dorsally. It then turns posteriorly and finally 

 dorsally so as to form a second curve, with the concavity dorsal this time, and thus reaches 



