365 



chinus, of course, must be combined with Echinopsis unless 

 perforate and imperforate tubercles may constitute a sufficient 

 character for the discrimination of the genera. 



Of this living type I know but one species which belongs to 

 the Cabinet of the Society. It was found at Key West, (Florida.) 

 It is: 



1. H. GouLDii Girard. General form, nearly circular; lower 

 surface slightly concave around the mouth ; upper surface rather 

 depressed than conical. The tubercles are but little prominent, 

 the larger ones, distant from each other, form a double row in 

 the ambulacral spaces. In the intermediate space between the 

 larger tubercles as well as between the pores, there are a few 

 smaller tubercles without regular arrangement. The tubercles 

 of the interambulacral spaces are disposed in three double rows, 

 of which only one reaches the summit. The outer row is rather 

 diffijse and composed of tubercles of a smaller size, resembling 

 those which are scattered between the rows. The spines are 

 short and slender, the longest three eighths of an inch in length. 

 All of them are cylindrical, varying in size according to the size 

 of the tubercles themselves. The plates are covered with a 

 minute granulation. The extremities of the teeth are very acute. 



Genus Melebosis Girard. 



This genus is intermediate between Salmacis and Temno- 

 pleurus, but differs from the first in having the ambulacral pores 

 disposed in three oblique pairs, and from the latter by the want 

 of deep impressions at the union of the plates where small holes 

 only are seen, as in Salmacis. The tubercles are slightly crenated 

 but not perforated. The auricles, or support of the masticating 

 apparatus, are thin, elevated, contiguous, forming a beautiful 

 crown. 



2. M. MiRABiLis Girard. Species measuring over one inch 

 and a half in horizontal diameter. General form, hemispherical ; 

 inferior surface nearly plane. Tubercles of equal size on both 

 ambulacral and interambulacral spaces, but sensibly larger on 

 the inferior surface. The plates of the ambulacra are narrower 

 than those of the interambulacra, and there is a large tubercle 

 on each. The tubercles of the ambulacral spaces are more 

 numerous than the others. The mouth is slightly notched. The 



