Massy — The Gijmnosomatous Pteropoda of the Coasts of Ireland. 237 



Cephalobrachia Bonnevii, sp. n. 

 (Plate VIII, fig. 4.) 



S.E. 529— Tow-net at 40 fathoms. One. 



Body shaped like Clione (PI. viii, fig. 4a), posterior end very narrow; 

 total length 2 - 50 mm. Eeproductive organs much expanded beneath the 

 skin at the right side. Fins very narrow at base, broadening rapidly. 

 Posterior lobe to foot small and pointed, and without a tubercle. No lateral 

 gill or ciliated bands. Skin unpigmentecl. No buccal cones or aceta- 

 buliferous appendages. Eadula : 5-1-5 (fig. 4 b), median tooth sickle-shaped 

 with at least three denticles on a straight margin. Lateral teeth moderately 

 long with square bases. The radula contained at least twenty rows of teeth. 

 Unfortuuately, owing to its minute size, I failed to find it after boiling it in 

 caustic potash, so that the foregoing description, and the figure, are based only 

 on sketches and notes made on seeing it dimly through the tissues after 

 dissection. It was large in comparison to the size of the animal. Subse- 

 quently, I found that in the case of a very minute buccal mass a sufficiently 

 good preparation could be made by placing it in a single drop of caustic 

 potash on a slide, and holding it thus situated over a flame instead of putting 

 it in a test tube. About sixteen very long hooks (fig. 4 c), curved at the 

 ends, were present in each sac, and closely resembled those of Cephalobrachia 

 macrochaeta, Bonnevie, so that, in spite of the differences presented by the 

 radula, it seems better to place the species provisionally in that genus. 



Family NOTOBBANCHAEIDAE. 



Notobranchaea tetrabranchiata, Bonnevie. 



S.E. 270 — Midwater otter trawl at 350 fathoms. Two. 

 S.E. 302— Midwater otter trawl at 300-350 fathoms. Three. 

 S.E. 476 — Midwater otter trawl at 300 fathoms. One. 

 S.E. 1237 — Midwater otter trawl at 450 fathoms. Five. 

 S.E. 1243— Tow-net on trawl, 670-692 fathoms. Two. 

 S.E. 1451 — Midwater otter trawl at 400 fathoms. One. 



These fourteen specimens measure 4-16 mm. in length. Some are long 

 and narrow, others are short and broad, the extreme of the latter form being 

 reached by the specimen from station S.E. 475, which measures 6 mm. in length 

 by 9 mm. in breadth. All the specimens have had the buccal mass examined, 

 and the radula was found to be in close agreement with the figures given by 

 Bonnevie (1913, p. 75 b) for the type. The outer lateral teeth, not shown 



