ECHINONEUS SEMILUNARIS. 333 



genus of this subfamily, though probably other genera will eventually be asso- 

 ciated with it. The Echini forming this genus are not large; the test is thin, 

 ovoid; there are no teeth. The actinostome is central and oblique to the 

 longitudinal axis, has no phyllodes nor bourrelets; the anal system is ex- 

 tremely large, more or less pyriform, situated between the mouth and the 

 posterior extremity. The tubercles are large, numerous, arranged in more 

 or less regular rows, no mammary boss, neither crenulated nor perforate. The 

 ambulacra are simple, extremely narrow, extending unbroken from apex to 

 mouth, the poriferous zone forming a narrow vertical band of simple pairs of 

 pores. The presence of so-called glassy tubercles, not carrying spines, irregu- 

 larly scattered over the test, is a striking feature of this genus. Abactinal 

 system ill defined, four genital pores, spines short, ambulacral suckers pro- 

 vided with disks as in the regular Echini. 



Echinoneus semilunaris 



Echinus semilunaris Gmei.. 1788. Linn., Syst. Nat. 

 I Echinoneus semilunaris Lam. 1816. A. s. V. 



PI. XIV. f. 1-5. 



Liitken, like myself, has only been able to recognize one species in the 

 West India Islands. As is well known, the difficulty of distinguishing the 

 species in this genus is very great ; the more so, as thus for only tests with- 

 out spines, and without buccal or anal membranes, from uncertain localities, 

 have been used in the determination of species. The Museum has specimens 

 from Cuba, Hayti, and the West Indies, which I have been unable to distinguish 

 by any characters given as specific by Desor in his Monog. des Galerites. The 

 arrangement of the tubercles and of the glassy tubercles is so different in 

 various parts of the test, and in specimens of different sizes, that it is 

 impossible to separate, witli any degree of accuracy, the species recognized 

 by Desor, and which had already, in the Catalogue Raisonne, been consider- 

 ably reduced in number. Having, fortunately, in the Museum Collection, 

 specimens which, without any doubt, were collected at the Sandwich Islands 

 and the Kingsmills Islands, I am able to give a comparative description of 

 the two species I have been able to identify. This will be the more complete, 

 as in some of the Sandwich Island specimens the anal and buccal membranes 

 are still retained, while M. Pourtales has collected a living specimen with 

 all its spines at Carysfort Reef. I had, in the Bulletin of the Museum of 

 Comparative Zoology, adopted the name of E. elegans Des. as the only name 

 given to specimens which undoubtedly came from the West Indies. Liitken 



