1843.] 



233 



1. Ophiura Murravii, inferior surface (n.s.). 



2. Ophiura serrata. a. part of arm, n.s. b. joints of arm magnified. 



3. Amphiura Pratti. a. part of disk and arm, n.s. b. joints of arm magnified. 



4. Section of arm of OpModerma Egertoni. 



5. OpModerma tenuibrachiata, part of disk and arm. a. Section of arm. 



The following Ophiurites are either new, or hitherto uncharacte- 

 rized as British : 



1. OpModerma tenuibrachiata, F. — The disc is similar to that of 

 0. Egertoni, but the rays are much longer in proportion, and less ta- 

 pering. They have a more flexible aspect than those of the O. 

 Egertoni, and present in their section, a different form of the central 

 ossicula ; for these, instead of being trilobate, are oblong with a tri- 

 angular central anterior lobe. Discovered in the lias at Bridport 

 by Dr. Murray of Scarborough and communicated by Mr. Bower- 

 bank. Mus. Murray. 



2. Amphiura Pratti, F. — The specimen presents the under surface 

 of the animal, the disc, which was probably soft or cartilaginous, 

 having disappeared, though its limits are well-marked by the forms 

 of the ossicula composing the bases of the arms, which were inserted 

 into it. There are traces of a few smooth, imbricated scales on the 

 intermediate plates beneath. The arms are nearly six times as long 

 as the diameter of the disc, and are slender and flexible, but not ta- 

 pering. The inferior ray-scales are quadrangular, with oblique sides. 

 Each lateral ray-plate bears a row of slender, conic, diverging, smooth 

 spines, which are about as long as the breadth of the ray. There is 

 also a very small spine at the inferior angle of each. 



This curious star-fish, which presents most of the characters of the 

 genus Amphiura (Linnean Transactions, vol. xix. pt. ii. p. 150), was 

 discovered by Mr. Pratt in the Oxford clay. Mus. Geol. Soc. 



3. Ophiura Murravii, F. — The disc is large in proportion to the 

 arms, and appears to have been covered by large scales. The ova- 

 rian plates are scutiform and rather small, projecting on the disc ; 



