1883.] SPECIES OF HOLOTHUROIDEA. 61 



which 6 are internal to the rest ; retractors fairly stout, very short. 

 Polian vesicles two, rather short, irregular in shape. Genital tubes 

 numerous, of some length, extendiug back as far as the middle of 

 the body ; the last division may have four terminal branches. 



The calcareous ring is remarkably well developed, the radial pieces 

 being very stout and broad, a little hollowed externally, with the 

 backwardly directed processes short and feeble ; the proximal end of 

 the interradial piece is constricted (fig. 5 6). 



The only calcareous bodies that vyere detected either in the skin, 

 which is not remarkably thick, or in the walls of the suckers were 

 stoutish discoidal bodies the perforations in which may be rare and 

 small. They are present in large numbers. 



Length 80 milhm., breadth about 50, length of calcareous ring 14, 

 Polian vesicle 10. 



Colour — ground-colour white, the trivial surface with blotches of 

 dark brown ; lighter brown spots, lines, or . patches may be seen on 

 the bivium. 



Hub. Bay of Honduras. Collected by G. E. Dobson, M.B., and 

 presented by him to the British Museum. 



I have the pleasure of associating with this species the name of its 

 discoverer, a name well known to all zoologists. 



Stereoderma murrayi. (Plate XV. figs. 6, 6 a, 6 b.) 



I have been for some time acquainted with a second species of this 

 remarkably firm-bodied genus, an account of which will appear 

 in the forthcoming report on the zoological collections made by 

 H.M.S. 'Alert.' It has fortunately happened that that new species 

 is particularly well represented ; and the supply of specimens has 

 enabled me to note that there are considerable variations in the 

 arrangement of the suckers in the " double row," and that the 

 regularity of this may become considerably obscured. 



Fortified by these examples, I have less hesitation than I should 

 otherwise have had in associating with this genus a single, rather 

 small specimen from the seas of Kurrachee, which the British 

 Museum owes to Mr. Murray. I venture to associate the name of 

 this energetic curator with this interesting new species. 



Tentacles small, dark ; retractors exceedingly delicate, though 

 with a broad base of origin ; Polian vesicle very long and narrow ; 

 oesophagus covered with a calcareous plating, much as in Thyone 

 sacellus (see Selenka, Zeitschr. f. wiss. Zool. xvii. pi. xx. fig. 115). 

 (Plate XV. fig. 6 6.) 



Integument very thick, and filled with strong-walled firm cor- 

 puscles, not so thick, however, as in 6'. unisemita, or so large as in 

 B. validum. 



Skin white in colour, the double row of the suckers only well 

 developed in the anterior third of the body, but better developed 

 behind than in the middle. 



About 30 millim. long and 1 1 wide ; of the same, or nearly the 

 same, width along its whole extent. 



Hub. Kurrachee. In exchange with the Kurrachee Museum, 



