310 Verrlll, Notes on Madiata. 



Test much depressed, becoming gradually very flat toward the 

 margin ; highest part at the middle of the anterior ambulacrum. 

 Margin broadly rounded posteriorly, the widest place opposite the 

 middle of the posterior ambulacra ; sides wavy, converging somewhat 

 toward the anterior side, which is slightly emarginate in the middle. 

 The posterior opening is rather oblong, relatively nearer to the center 

 than in most species ; the other openings are elliptical, the anterior 

 one shortest. The rays are broad, shorter than usual, especially the 

 anterio-lateral pair. The genital openings are large, and form a 

 regular pentagon. The anal opening is situated about midway be- 

 tween the mouth and posterior foramen. The sulcations of the lower 

 surface are very distinct and much branched. 



Color deep reddish brown, or dark greenish brown. 



This species can readily be distinguished from E. emarginata, and 

 its varieties, and E. Michelini of the West Indies, by its broader 

 form, narrowing anteriorly ; by the relatively broader and more 

 equal, ambulacra ; and by the position of the posterior foramen, it 

 being half its length nearer the center than the posterio-lateral ones. 



Dr. Ltitken, apparently with good reason, refers the Echinus tetra- 

 pora Gmelin to the E. emarginata of the West Indies. Our species 

 appears to be the one well figured and described by Prof Agassiz 

 under the former name, and will, therefore, require a new designation. 



The specimen figured by Agassiz is smaller than any of ours, and 

 had the posterio-lateral lunules still open, while in all the specimens 

 that I have seen they are completely closed, unless opened by reason 

 of some injui-y. 



EnCOpe grandis Agassiz, op. cit., p. 37, Tab. 6. 



Two specimens, apparently belonging to this species, are in our col- 

 lection, one of which, received from the Boston Society of Natural 

 History, is labeled as coming from the Gulf of California, and the 

 other, presented by Mr. Horace Mann, was obtained by him from 

 Mr. Pease, with several other characteristic Panamic and Californian 

 Echinoderms, but without any authentic locality.* 



The latter agrees perfectly with the figure and description by Agas- 

 siz. The origin of his specimen is unknown, but it was supposed to 

 have come from the Antilles. Owing to lack of perfectly authentic 

 localities, I prefer to avoid confusion and possible error by omitting 

 descriptions until more authentic specimens can be obtained. 



* Several dozens of large and fine specimens have recently been sent from La Paz 

 bv J. Pedersen, — Reprint. 



