220 DR W. A. HERDMAN ON 



Leptoclinum, n. sp. 



One colony from Tangier Bay ; 35 fathoms. 



Didemnum, sp. 



One colony from Station 54 (Freroe channel, " cold area ") ; 363 

 fathoms. 



BotnjUus, sp. 



One colony from Tangier Bay ; 35 fathoms. 



BotryUus t sp. 



One colony from Station 54 (Fseroe channel, "cold area"); 363 

 fathoms. 



Some of these possess an interest, apart from their morphological pecu- 

 liarities, on account of the considerable depths from which they were obtained. 



ASCIDIA SIMPLICES. 



Family Ascidiid^e. 



This family is represented in the collection by three species of Ascidia. 

 The common Ciona intestinalis was apparently not dredged at any of the 

 localities visited. 



Ascidia scabi'a, O. F. Midler. 



About thirty specimens of this well-known species, most of them attached 

 to Lamellibranch valves, were dredged in Lough Foyle, Ireland, from a depth of 

 10 fathoms, during the first cruise of the " Porcupine " in 1869. Most of them 

 are small. They range from 5 mm. to 25 mm. in greatest length. The shape 

 varies considerably. The small individuals are ovate and much flattened; 

 the larger ones are usually irregularly orbicular, but a few are oblong, and 

 resemble the typical form of Ascidia virginea. The mantle is strong, and the 

 muscle bands run very irregularly. 



In some remarks upon this species published in 1880, I showed how vari- 

 able the branchial sac might be in the arrangement of the stigmata. * The 

 " Porcupine " specimens exhibit this irregularity, and, in addition, show in 

 some places an imperfect development of the internal longitudinal bars, which 

 is frequently observed in Corella parallelogramma, and which I have figured 

 in Ascidia triangularis A In 1880 I described the meshes in Ascidia scabra 



* "Notes on British Tunicata," Journ. Linn. Soc. Zool, vol. xv. No. 85, p. 274. 

 f Loc. cit., pi. xvi. fig. 6. 



