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 raisonné’ with this re-- 
mark: “ Mais l’anus est un peu plus bas, et la face supérieure 
plus surbaissée.” 
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 Desmaresti, Goldf. 
Syn. Spatangus Desmarestii, Goldf. Petref. p. 153. tab. 47. fig. 4 a—e ; 
Agassiz and Desor, Cat. raisonné, Ann. Sc. Nat. tom. vill. 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 plano- 
a a i i te 
