from the Island of Malta. 97 
shaped as that species; the single ambulacrum is larger and 
wider, and the antero-lateral pair are more developed in the 
German than in the Maltese form; they resemble each other 
in the interambulacrum in both possessing a tail-like terminal 
process, and in having the posterior border obliquely scooped 
out ; they are both, likewise, Miocene Urchins, S. acuminatus 
being found in that terrain near Cassel and Dusseldorf (Ger- 
many), and at Bordeaux and Blaye (France). 
Affinities and differences.—The depth and length of the am- 
bulacral areas, with the great declivity of the anterior side of the 
test, and the post-discal carina, with its caudate-like process, 
serve to distinguish this species from H. Scilla. 
Locality and stratigraphical position—Collected from bed 
No. 4, the calcareous sandstone at Malta. We dedicate this 
species to our friend M. Cotteau, the learned author of ‘ Etudes 
sur les Echinides Fossiles du département de Yonne,’ who has 
most generously aided us in our studies, by contributing the 
types of many of his species to our cabinet for comparative in- 
vestigations. 
Hemiaster Scille, Wright, n. sp. Pl. VII. fig. 1 a-f. 
Syn. Spatangus crassissimus, Desmoulins, Etudes sur les Echinides, 
p- 394. no. 30. 
Echinus, Scilla, Corp. Mar. pl. 10. fig. 4. 
Test globular, higher behind than before; ambulacral areas 
short; single ambulacrum the longest, forming a deep sulcus 
on the anterior border; antero-laterals wide, diverging at an 
angle of 44°; postero-laterals not half the length of the ante- 
riors, forming an angle of 56°; both pairs form sulci on the 
sides of the test: posterior border squarely truncated down- 
wards and outwards: the anus high near the dorsum: base 
convex: mouth at the anterior third, with a large projecting 
under lip. 
Dimensions.— Antero-posterior diameter 1,%, mch, transverse 
diameter 1,7, inch, height 1,4, inch. 
Description.—Much confusion has arisen as to the identity of 
this Urchin, occasioned probably by the circumstance of Scilla 
having figured only the base of the test, and neglected to give 
either its profile or the dorsal surface. In M. Agassiz’s ‘ Pro- 
dromus’ it was entered as Micraster Goldfussti, but has been 
omitted from Agassiz and Desor’s ‘ Catalogue raisonné. M. 
Desmoulins identifies it with the Spatangus crassissimus of 
Defrance, but on referring to the origimal description * of that 
species, we find that Defrance’s species came from “la craie 
* Dict. Se. Nat. tom. 50. p. 96. 
