EOHINOIDEA. 36 



Taking all things into consideration H. compressua although very closely 

 related to H. pyrenaicus may be easily distinguished in well preserved specimens ; 

 but if these are deformed or crushed in tbe smallest degree, the determination 

 becomes nearly impossible, since other features, as the shallower an teal sulcus or the 

 position of the anal opening, are in this case also affected and deformed. 



EamiJy: SPATANGIBM. 



Subfamily: SPATANGIN^. 



Genus: HEMIASTER, Desor. 



Hemiasteb blanpordi, spec. nov. PI. VIII. fig. 3-3a. 



Length L =27 27 25 



Breadth b =25 25 22 



Height h =22 21 19 



— c =-92 -92 -88 



-J* =-81 -78 -76 



L 



The rather small globular test is subelliptical ir* shape, just a little longer than 

 it is broad ; posteriorly it is only slightly alluminate ; the posterior side a little 

 truncated ; upper surface highly inflated ; lower surface tumid, a little flattened 

 anteriorly ; ambitus rounded ; highest point of the upper surface in the posterior inter- 

 ambulacrum just above the periproct ; from there the profile line drops nearly per- 

 pendicularly in a posterior direction, while forwards it slopes a little o^ore gently till 

 about the end of the single ambulacrum, when it also drops quite suddenly in a 

 perpendicular direction. 



Apical disc central, small and compact ; four genital plates perforated by large 

 holes. The anteal sulcus is moderately broad and deep on the upper surface, but it 

 becomes narrow and very shallow at the ambitus, thus hardly indenting the anterior 

 margin. 



The single ambulacrum which is lodged in the anteal sulcus, is moderately 

 long and open at the end; the poriferous zones are narrow and composed of minute 

 pores arranged in oblique pairs. The grooves for the antero-Iateral ambulacra are 

 somewhat shorter, moderately deep, and rather broad at the end, continuing in the 

 shape of narrow and shallow depressions towards the ambitus. The poriferous zones 

 are broader than the inter-poriferous ones and composed of rounded conjugate pores 

 which are arranged in horizontal pairs. The postero-lateral ambulacra are very 

 short, and lodged in rather shallow grooves, the continuations of which also form 

 narrow and shallow depressions as far as the ambitus. The inter-ambulacral areas 

 are slightly swollen, the posterior one rising as a rounded keel. The periproct 

 is vertically elliptical, and situated at the upper end of the truncated posterior side. 



■s % 



