112 Dr. T. Wright on Fossil Echinoderms 



interambulacrum is narrow, and forms a conspicuous prolon- 

 gation or beak-like process, which arches over the upper border 

 of the round anal opening, situated rather below the middle of 

 the posterior border, in an oblique truncature of the test : this 

 beak-like process is not seen in the small specimens before us ; 

 it would therefore appear to be a character of the adult con- 

 dition only. The base is slightly concave towards the mouth, 

 which is situated nearer the anterior border ; it has a pentagonal 

 form, with five small oral lobes covered with tubercles ; between 

 them, the terminations of the ambulacra form five short pori- 

 ferous petals. The tubercles on the upper surface are small and 

 irregularly disposed on the plates ; those on the base are a little 

 larger, especially in the vicinity of the mouth. 



Affinities and differences. This species resembles Catopygus 

 fenestratus from the upper chalk of Ciply, Belgium, but is di- 

 stinguished from it by having the sides more tumid and the 

 upper surface flatter ; the posterior border is likewise more pro- 

 duced ; it distinctly differs from it however in having the base 

 slightly concave, and the oral lobes less developed. It differs 

 from Nucleolites (Pygorhynchus] subcarinatus, Goldf., from the 

 middle tertiaries of Biinde, in having more tumid sides, a less 

 concave base, and a different form of the anal opening. From 

 the very brief notice of Catopygus conformis, Desor, from the 

 tertiaries of Orglande, it is impossible to form any idea how far 

 it may resemble that form, as it is neither figured nor described, 

 but merely entered in the ' Catalogue raisorme ' with this re- 

 mark : " Mais Tanus est un peu plus bas, et la face superieure 

 plus surbaissee." 



Locality and stratigraphical position. Collected from bed 

 No. 1, Malta, where it is extremely rare. Specimens are in the 

 collection of the Geological Society, the Jermyn Street Museum, 

 and the cabinet of Earl Ducie. We dedicate this species to 

 Dr. Vassallo of Malta, under whose judicious care and continued 

 research the public collection of Maltese fossils has been greatly 

 enriched. 



Spatangus Desmarestii, Goldf. 



SYN. Spatangus Desmarestii, Goldf. Petref. p. 153. tab. 47. fig. 4 a-c ; 

 Agassiz and Desor, Cat. raisonne, Ann. Sc. Nat. torn. viii. p. 7. 



Test cordate, arched and carinated ; anteal sulcus broad ; peta- 

 loid portion of the antero-lateral ambulacra long, narrow, and 

 curved outwards and a little backwards, angle of inclination 

 18 ; postero-laterals long and narrow, angle 60 ; only a few 

 moderate-sized tubercles on the interambulacral plates between 

 all the ambulacral areas; border slightly obtuse; posterior 

 part truncated ; anal opening transversely oblong ; base piano- 



