THE " POPCUPINE " AND " LIGHTNING " TUNICATA. 229 



siderable number of internal longitudinal bars, do not project much into the 

 cavity. The sac, as a whole, is very similar in structure to those of Styela 

 oblonga, S.fia/ca and S. glans* 



The dorsal tubercle is very simple, the prebranchial zone is narrow (Plate 

 XXXVI. fig. 6), and the peritubercular area small, and not occupied by the 

 tubercle. The tentacles are of considerable size, and have large bases. 



Polycarps are not very numerous. They are scattered over the inner surface 

 of the mantle (Plate XXXVI. fig. 4, g.). They are unisexual. The male poly- 

 carps are deeply cleft into lobes. 



The alimentary canal lies on the dorsal part of the left side of the body. 

 The stomach is pyriform, and is strongly ribbed externally ; the intestinal loop 

 is moderately open, and the rectum is long and narrow (see Plate XXXVI. 

 fig. 4, v.). 



Family MolgulidyE. 



This family is represented in the collection by two species of Molgula and 

 the common Eugyra glutinans. 



Molgula, sp. 



A single small specimen of a Molgula, slightly torn, was found adhering to 

 one of the specimens of Polycarpa pomaria from near Belfast ; 70 fathoms. 



The shape is nearly globular; 8 mm. in diameter, and slightly compressed 

 laterally. Short hair-like processes project all over, and have a few grains of 

 sand and other foreign bodies attached to them, but there is no incrusting coat. 

 The test is moderately thin, soft, and nearly transparent. The colour is light 

 yellowish-grey. Possibly this may be Molgula nana, Kupffer. 



Molgula ampulloides, van Beneden. 



One specimen of this rather widely-diffused species was dredged in Lough 

 Foyle, during the first cruise of the " Porcupine " in 1869, from a depth of 10 

 fathoms. It measures 17 cm. in length, and 1*4 cm. in greatest breadth. 



Eugyra glutinans, Moller (Plate XXXVI. figs. 12-14). 



Eighteen specimens of this common and apparently gregarious species were 

 dredged in Donegal Bay, Ireland. 



None of the specimens are large. They range from 4 mm. to 12 mm. in 

 greatest diameter. The incrusting sand is very fine and comes off readily, the 

 result being that most of the specimens have very little left, and in some the 

 delicate test is almost completely exposed. 



* See Eeport upon the Tunicata dredged during the voyage of H.M.S. " Challenger," Part I. 

 Plate XX. figs. 4, 8, and 11. 



