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ECHINODERMATA. 



The followiug notes ou the Echinodermata have been 

 made by Mr. Johnston, some of which I have examined 

 and compared the species, and added the specific names, 

 with a few verbal aUerations. 



MicRASTEii BREvisTELLA. Laubc. Rather more rounded 

 than Laube's figure. It is slightly compressed dorsally ; 

 central surface concave. The anal orifice is triangular in 

 appearance, with the apex towards the " plastron,^^ and is 

 situated on the posterior of the ventral surface. 



The plastron is round, and is situated near the middle 

 of the concave ventral surface. The five ambulacra radiate 

 from the apical disc in a graceful though slightly irregular 

 manner. The pores 27 to 37 double pairs on each ambu- 

 lacrum, extend about half way over the dorsal surface ; 

 and from the extremities of each double pair, the two 

 grooves are continued round to .the ventral surface, and 

 thence to the plastron. The groves may be described as 

 irregularly parallel to each other. The whole surface is 

 densely covered with rather small tubercles, uniform in 

 size, and surrounded by scrobicula. 



MicRASTER ETHEKiDGEi. U.S. Tcst Small, oval, dcpressed, 

 and surface very much flattened ; ventral slightly con- 

 cave; ambulacral groves 5, well marked and continued 

 from apical disc ou the dorsal surface to the plas- 

 tron on the ventral surface ; anal orifice, small, round, 

 situated at the posterior ventral margin ; plastron, 

 central, round. The whole test covered densely with 

 tubercles, small, but irregular in size and distribution. 

 The dorsal surface is too imperfectly preserved to make 

 out the apical disc or ambulacral pores clearly. 



Hemipatagus woodsii (var. a) Cordiform. Differs from 

 H. ivoodsii in the following particulars : — Apical disc 

 contains 5 ocular plates, and is situated nearer to anterior 

 end of test madreporiform body angular : odd ambulacral 

 groove, much shallower than in H. Woodsii. 



Primary tubercles greater in number ; occasionly one 

 primary tubercle is found situated on the posterior inter- 

 ambulacra. Great breadth nearer to anterior and than 

 upon H. woodsii. Dorsal surface much more flattened and 

 depressed. 



Note. — Prof. Duncan has lately shown that Hemijjatagns 

 is a genus identical with the living Lovenia, Gray. 



