462 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.45. 



branchial band, p. g., and further toward the branchial orifice still 

 another ridge, or fold, less prominent than the last, e. f. In 

 all, consequently, four epithehal ridges encircling the branchial 

 orifice, two (those of the peribrancliial band proper) external to the 

 tentacle circlet; and two witliin the circlet, e. f. and e. f. Dorsal 

 lamina a plain narrow ridge, with intimations of ribbing in some 

 specimens. Branchial membrane, 6 folds (counting rudiments) on 

 each side. The typical number of longitudinal vessels on the folds 



as follows: 



^ , , , f 1 -^-0-7-0-5-1- // L. 

 EndostyleJ o-^-O-^-O-^-O-^-l-H R. 



From this it appears that the second and sixth folds on the left, and 

 the second on the right are marked by a single longitudinal vessel. 

 There are no vessels between the folds. Tliis scheme, with shght 

 variations, holds for the four specimens examined. Stigmata nearly 

 straight, but irregular in length, from 14 to 20 in the mesh; about 

 six prominent transverse folds or ridges on the outer surface of the 

 sac; a series of large transverse vessels on the inner surface of the 

 sac separating generally the series of stigmata, and a large number of 

 fine vessels extending across the stigmata (fig. 13). Ganghon long and 

 narrow, its anterior end adjacent to the hypophysis. Atrial tentacles 

 very long in proportion to thickness, about 16 in number forming a 

 circlet around the atrial orifice; within the circlet and close to the 

 bases of the tentacles a cihated epithehal fold wliich may be called 

 a periatrial fold, p. a. f. (fig. 12). 



In close association with the atrial tentacles numerous tubercles 

 produced by parasites (suctoria), embedded in the epithehal lining 

 cf the region (fig. 12). 



Alimentary system. — On the left side of body, loop simple but 

 narrow; stomach not distinctly differentiated from intestine, two 

 folds in stomach wall; "fiver" well developed, consisting of a great 

 number of more or less independent alveofi (fig. 10). Renal organ 

 present ( ?) on right side near base of branchial sac. 



Reproductive system. — On both sides of body, that of the left cross- 

 ing the dorsal hmb of the intestinal loop, more or less cyhndrical, 

 surrounded by the more voluminous many-lobed testes (fig. 10, 

 gon.). A few structures, resembhng the so-called endocarps of 

 Sty eta and its allies present. 



This unique species possesses a combination of characters that 

 suggests relationsliips in various directions. The long, slender 

 peduncle reminds one of the genus Rhizomolgula, and also of some of 

 the Boltenias, and of Culeolus. With tliis feature, however, resem- 

 blance to these genera ends. On the whole the animal would seem 

 to approach Microcosmus more closely than any known genus. 

 Sluiter (1900, p. 31) has described a member of this genus, M. minia- 



