BATHYDORIS. 19 



DOTO (OKEN). 



THE members of this genus are small animals, probably of cosmopolitan distribu- 

 tion. They are recorded in abundance from the Northern and Median Atlantic (Cape 

 Verde Islands) and the Mediterranean, and also from Mauritius, Zanzibar, Ceylon, and 

 Formosa. A great number of species have been described, especially by Trinchese and 

 Hesse, but the majority are uncertain, as it is hard to find good specific characters. 

 The buccal parts and other internal organs are much the same for all species, and not only 

 the colouration, but such characters as the shape of the rhinophore sheaths, frontal ridges, 

 and tubercles vary within the limits of one species. Dr. Bergh recognises sixteen 

 species in his " System der Nud. Gasteropoden," but of these D. arbuscula Agassiz and 

 D. minuta Forbes appear to be mere names, and D. australis Angas is probably a 

 Melibe. To the list may be added D. afncana Eliot (P.Z.S., 1904, page 285), D. 

 annuligera Bergh (Siboga Exped. Opisth., 1905, page 221), and D. floridicola Simroth 

 (Archiv. fur Naturgeschichte, 1888, Vol. I., page 219), though the last (the radula 

 being unknown) may perhaps be identical with Bergh's Dotilla pygmaea. Doto crassi- 

 cornis is recorded from Christiania, so the genus is probably found in Arctic seas. 



6. DOTO ANTARCTICA, sp. n. (?=D. fragilis var). 



ONE specimen labelled "25.2.02., Seal crack W.Q. 45." The body is 11 mm. long, 

 4 mm. high, and 3 mm. broad, without the cerata, the largest of which is 5 mm. high 

 and 2 5 broad. The colour as preserved is a uniform deep bright yellow, except that 

 the tips of the tubercles on the cerata are paler. The surface. of the body is smooth, 

 and there are no tubercles on the back or sides. From the marks left on the skin, it 

 would appear that there were originally six pairs of cerata, but only six single cerata 

 have been preserved. They are erect, tall, but not very stout, and bear four to five 

 rows of distinct pointed tubercles. In the top row there are four tubercles, in the 

 lower as many as eight. The facets of the cerata, which have been removed, show three 

 distinct openings, one for a ramification of the liver and two for the vascular system. 

 The foot is broad and rather paler than the body. The frontal veil is ample, rounded 

 in front, and bears two ridges running to its edge from the front of each rhinophore 

 sheath. These sheaths are 2 mm. high. Their margin is divided into four lappets, of 

 which the most anterior is conspicuously larger than the others, and projects 1 3 mm. 

 in front. The rhinophores are rather stout and quite smooth, without wrinkles. The 

 genital opening is under the place where the first of the cerata apparently stood and the 

 anal papilla at the right anterior extremity of the pericardium, between the first and 

 second cerata. 



No jaws were found, but these organs are probably not absent. In this genus 

 they are extremely thin and membranous, so that, except in large and well preserved 

 specimens, they are very apt to become torn or decayed, and so escape notice. The 

 radula is a single row of 102 clear yellow teeth of the shape usual in the genus. 



