CLIONIDAE 29S 



T. gegenbauri is thus characterized by Mme Pruvot-Fol (1926, p. 29) : " Lobes du pied 

 reunis; partie cephalique beaucoup plus volumineuse que I'abdomen; crochets tres 

 longs, greles; dent mediane rectangulaire, a tranchant onduleux, ne recouvrant pas 

 entierement sur les cotes la plaque basale; intermediaire a cuspide courte mais aigue; 

 marginales toutes semblables, courbes, aigues, non aplaties". 



The above specimens were taken north-east of the Falkland Islands. They measure 

 15-19 mm. in length. Two have lost their buccal parts. The radula of the other two is 

 like that of the type. They are more than twice the length of Irish specimens and the fins 

 are wider apart, and the viscera occasionally extend to the end of the body, which is 

 sometimes rounded. I agree with Mme Pruvot-Fol that the small specimens, measuring 

 3-7 mm., named by me (1917) T. atlaiiticus, are referable to the above. As this author 

 remarks (1926, p. 28) it is always useful to give a figure of a rare species, as so often the 

 radula may take a slightly difi^erent direction on the slide which entirely changes the 

 aspect of the various teeth. Thus in the specimens recorded above, the median tooth is 

 much more like that figured by Mme Pruvot-Fol {loc. cit., pi. iii, fig. 74c) than Boas' 

 illustration (1886, Tab. 8, fig. 122). 



Distribution. Messina (Boas, 1886). South-west Ireland (Massy, 1909, and 1917 as 

 T. atlanticiis). North Atlantic, ofi" Portugal to the Azores, 0-1500 m. (Pruvot-Fol, 

 1926). 



Thliptodon diaphanus, Meisenheimer, 1905. 



St. 297. Young-fish trawl, 200-300 (-0) m. : i specimen. 



This specimen, measuring 7 mm. in length, was taken off the Cape Verde Islands. 

 The radula, especially the median tooth, agrees far more closely with the example 

 figured by Mme Pruvot-Fol (1926, PI. iii, figs. 79) than with Meisenheimer's illustration 

 (1905, pi. xxvii, fig. 3). Mme Pruvot-Fol {loc. cit., p. 28) thus characterizes this species: 

 " Lobes lateraux et lobe median du pied separes par un grand intervalle. Dent mediane 

 a tranchant droit, intermediaire a cuspide tres courte, marginales en lame de faux, apla- 

 ties. Organe copulateur pourvu d'un appareil annexe: deux glandes et une ventouse". 



Distribution. Gulf of Guinea, St Thomas, Sumatra, Seychelles, Gulf of Aden 

 (Meisenheimer, 1905). Ascension I. (Schliemenz, 1906). S.W. Ireland (Massy, 1909 

 and 1917). Antarctic (Meisenheimer, 1906). Atlantic, between Madeira and the 

 African coast, 0-4000 m. (Pruvot-Fol, 1926). 



LIST OF REFERENCES 



Boas, J. E. F., 1886. SpoUa Atlantica. Dansk. Vid. Selsk. Skrift., Afd. iv, Bd. i. Kjobenhavn. 

 BoNNEViE, Kr., 1913. Pteropoda. Rep. Set. Results 'Michael Sars ' North Atlantic Deep-Sea E.xped., 11, Pt. I, 



Zoology. 

 Eliot, Sir Ch., 1907. Pteropoda. Nat. Antarctic Exped., Nat. Hist., in, vi. London. 

 Pol, Herm., 1875. Sur le developpement des Pteropodes. Arch. Zool. Exp., T. iv. 

 KwiETNiEWSKi, C, 1902. Alcune Osservazioni intorno agli Pteropodi Gimnosomi del Mare Mediterraneo. 



Atti See. Veneto-Trentina Sci. Nat., Serie ii, Vol. iv, Ease. 2. 



