ASCIDIA OBLIQ.UA. 125 



Length about two inches. 

 Ual>. Deep water. 



SCOTLAND.- Outer Haaf, Shetland [the type speci- 

 mens], dredged in from 40 to 50 fathoms [; between 

 the islands of Whalsey and Balta, Shetland, in about 

 the same depth of water] (Norman}. 



First record. Alder, 1863 ; coll. Norman [18(51]. 



Three examples of this species were obtained by 

 Mr. Norman in different stages of growth, the largest 

 measuring a little above two inches in length. A 

 somewhat larger specimen was sent to us from Sweden 

 by Professor Loven, with the name of Ascidia mentida 

 attached. A. obliqua has probably hitherto been over- 

 looked as a variety of that species, but it is perfectly 

 distinct ; the form is more ovate, the test very much 

 thinner and attached obliquely at the base, the aper- 

 tures are more distinctly grooved, and the branchial 

 sac has not the intermediate papillae, nor is it reflected 

 upwards at the base, as in A. mentula. It appears to 

 be a northern species. 



The test (PI. XI, fig. 10) does not appear to be well 

 supplied with blood-channels, as is the case in 

 A. me'iitidn, and the branchial sac (PI. XVIII, fig. 6) is 

 minutely and obscurely plicated longitudinally, the 

 plicae being wide and shallow ; there seem to be two 

 or three longitudinal bars to each plait. The papilla?, 

 which are large, with the extremity rounded and a 

 little enlarged, are not numerous, the reticulations 

 formed by the bars crossing the primary vessels being 

 rather coarse, and the papillary membrane not nearly 

 so extensively developed as is usual. There are about 

 seventeen slender, distant, tentacular filaments, with 

 a few small intermediate ones. The oral lamina is 

 broad, with the right side delicately ribbed, the ribs 

 being rather distant; and the branchial tubercle is 

 broad and loop-formed, with the concavity turned 

 upwards. The right hand extremity is a little bent 

 outwards. 



