62 THE VOYAGE OF H.M.S. CHALLENGER. 



In the mantle of this specimen the muscle Ijands are more distinct than in the case 

 of specimen A from Station 166. The "gill" or dorsal lamina (see PI. IV. fig. 6) has 

 very closely placed transverse ridges running transversely in irregularly convoluted 

 courses. The ridges are formed of columnar epithelium. 



There is evidently a considerable amount of variability in this large species. There 

 are some forms which have the test smooth (e.g. Challenger specimen D and Traustedt's 

 specimen^ ) and there are some which have it tuberculated (e.g. Challenger specimens 

 A and C, and British Museum specimen). It might be worth while to separate off the 

 latter as a variety echinata. Then the position of the nucleus is liable to variation 

 (compare PL IV. figs. 3 and 4, with fig. 1, and with Traustedt's figures). Lastly, the 

 dorsal tubercle may difier in shape and size in difi"erent specimens, as is shown 

 above. 



The anterior extremity of the endostyle extends forwards in front of the 

 peripharyngeal bands (see PL IV. fig. 7), and the right and left peripharyngeal grooves 

 are completely cut off ventrally from one another and from the groove of the endostyle. 



Traustedt has given figures of this species seen from the dorsal and ventral surfaces. 

 Plate IV. fig. 1, shows the Challenger specimen A seen from the left side, half the 

 natural size. 



Salpa, sp., (?) n. sp. (PL IV. fig. 9). 



External Apj^earance. — The shape is oblong, with the ends nearly equally wide, 

 and the dorsal and ventral edges almost straight. The branchial and atrial apertures 

 are terminal, large and bilaljiate. The nucleus is placed on the ventral edge of the 

 posterior end. On each side of the body there are several large tubular projections 

 with open ends. Length of the body about 1 6 cm. 



Tlie Test is moderately thick and firm. At the posterior end, over the region of the 

 nucleus, it becomes stifi'er and thicker than elsewhere. Along the posterior part of the 

 dorsal surface, and around the branchial and atrial apertures, there are a number of 

 large pointed tubercles. The tubular projections on the sides of the body are formed 

 by a prolongation of the test with a slightly thickened margin to the terminal aperture. 

 Otherwdse the surface of the test is smooth. 



The specimen from which the above description is drawn up is a fragment of a 

 lai-ge Salpa which was found in the same bottle with a fragment of Salpa costata- 

 tilesii (specimen B) from Station 168, off the east coast of New Zealand, July 8, 1874 ; 

 lat. 40° 28' 0" S., long. 177° 43' 0" E. ; surf temp. 57°-2. 



If it belongs to a new species, it is probably closely allied to Salpa costata-tilesii. 

 Unfortunately, only a portion of the test, including the branchial and atrial apertures, 



' See his figures 38 and 39. 



