from the Island of Malta. Ill 



small Nucleolite before us to the section Pyyorhynchus, which 

 is thus characterized by Agassiz : " Form elongated ; ambu- 

 lacra distinctly pctaloid, often costated as in Echinolampas. 

 Mouth central or subcentral, pentagonal, surrounded with five 

 large lobes, and a distinct rosette of buccal pores. Anus pos- 

 terior, nearer the superior than the inferior border." All the 

 species of the genus Pygorhynchus belong to the nummulitic 

 and tertiary rocks ; those of the genus Catopygus, with one ex- 

 ception, are cretaceous forms. 



Pygorhynchus Vassalli, Wright, n. sp. 



Test oblong, wider behind than before ; interambulacrum pro- 

 duced into a caudal elongation ; petaloid portions of the am- 

 bulacral areas narrow and short; sides tumid; anus small, 

 round, nearer the inferior border than the dorsum, with a 

 projecting beak-like process arching over its upper border, 

 and an oblique truncature of the lower part of the border 

 below ; base slightly concave ; mouth pentagonal, nearly cen- 

 tral ; oral lobes small ; rays of the poriferous star around the 

 margin short. 



Dimensions. Antero-posterior diameter 1^ inch, transverse 

 diameter T 7 ^ths of an inch, height nearly T ^ths of an inch. 

 Most of the specimens average only from one-half to two-thirds 

 of these dimensions. The large specimen before us is the most 

 perfect we have examined. 



Description. This small Urchin has an oblong form ; it is 

 rounded before, a little enlarged towards the junction of the 

 middle with the posterior third, which is produced into a caudal 

 process. The sides are tumid, and the upper surface is flat- 

 tened ; the petaloid portions of the ambulacral areas are narrow 

 and short, and form only a star on the dorsum ; the single and 

 postero-lateral areas are nearly alike in width and length ; the 

 antero-lateral pair are rather wider and shorter, they are /^ths 

 of an inch in length, and are slightly curved forwards and 

 outwards; their poriferous zones contain eighteen pairs of 

 pores, arranged in narrow rows, and not united by any apparent 

 slit. The postero-lateral areas are /^ths of an inch in length, and 

 their zones contain twenty pairs of pores ; these areas are directed 

 much backwards, which makes the width of the lateral interam- 

 bulacra proportionally greater. The apical disc is nearly central, 

 but nearer the anterior border ; it has four large genital pores, 

 and five well-marked eye-holes. The single ambulacrum is almost 

 identical in length and width with the posterior pair ; the apices 

 of all the ambulacra are rather rounded than lanceolate. The 

 lateral interambulacra we have said are very wide, but the single 



