284 ECHINOMETRA VIEIDIS. 



stout spines, has been the EcMnometra lobata Blaixv. ; the flatter, more cir- 

 cular variety, with long slender spines, has even been referred to a different 

 genus, Heliocidaris, by Hupe. Authors generally have referred the young 

 flat stage to Heliocidaris niexicana Ac 



Liitken supposed that the common West India Echinometra was the 

 Echinus lucunter of Linne, and both he and Professor Loven think the tradi- 

 tion of Linne's species points that way ; unfortunately the labels of the Coll. 

 Lud. Ulric. Reginae in the Museum of Upsala have been lost, so that it is 

 impossible with precision to determine what Linne meant, and as there is no 

 doubt as to what Lamarck meant by his E. lucunter, I have retained the 

 name for the common Pacific species, and would have retained for our 

 West India species the name E. acufera, as had been done before by Midler, 

 were it not that the types which have served as the Cidaris subangularis 

 of Leskc are still preserved in Erlangen, leaving us no choice in the 

 matter. 



It is somewhat remarkable that, with the extensive geographical distribu- 

 tion of this species (the whole coast of Brazil, the Gulf of Mexico, Caribbean 

 Sea, West India Islands, Bahamas, Bermudas, and W. coast of Africa), it 

 should be so limited in bathymetrical range. 



Littoral 6 1 1 > 7 fathoms, 



Echinometra viridis 



! Eclunomilni viridis A. Agass. 1803. Bull. M. C. Z., I. 



PI. X". /. l. 



At once recognized by its prominent bare abactinal system with equally 

 developed genital plates. The anal plates are large, bare, one or two 

 of the larger ones having a single spine, the genital plates carrying but a 

 single small tubercle near the anal edge; the ocular plates are completely 

 excluded from the anal system, the madreporic plate scarcely larger than 

 the other genital plates. The poriferous zone narrow, the arcs confluent, 

 the pores arranged in arcs of usually five, though sometimes six pairs. 



The spines in all the specimens examined are of a dirty green color, 

 tipped with olive, with frequently a white milled ring. The actinostome 

 is nearly circular, the actinal cuts shallow but sharp for this genus, the 

 auricles slender, short, with a large auricular opening and low connecting 

 ridges. The secondary rows of tubercles of the interambulacral space are 

 irregular, made up of small secondaries, and in ambulacra are mere granules. 



