1858.] BATE PROSOPONISCUS. 139 



The prominent eye so characteristic in the fossil is a feature 

 frequent among Isojpoda. It was this, as much perhaps as anything 

 else, that induced me at first to think that the fossil belonged to 

 that order of Crustacea. Although more common among Isopoda, 

 the prominent eye is not inconsistent with the structure of an Am - 

 phipod. It so exists in the genus Phlias of Guerin, and to a less 

 extent in Acanthonotus of Owen. 



Amphipods are generally laterally compressed ; they have the seg- 

 ments narrower and shorter than those of the pleon. The squami- 

 form coxae are absent in many of the fossil specimens, particularly 

 the anterior portion, — a circumstance that may be accounted for by 

 the known habits of the animal, since it spKts off the legs when it 

 frees itself from the integument in moulting. 



If the fossil be examined closely, each segment of the pereion will 

 be found to be elevated posteriorly and depressed anteriorly ; and it 

 will be seen that a deep notch exists immediately behind the poste- 

 rior margin of the first segment of the pleon. This imbricated 

 appearance is evidently the result of the upper dorsal portion of the 

 segments being on the stretch, while the lower or lateral margins of 

 the same overlap each other. This shows that the remains were 

 rolled upon themselves, — a condition which Crustacea very generally 

 assume. 



A feature, as before remarked, that is prominently peculiar in 

 this fossil specimen is the remarkable difference between the size of 

 the segments of the pleon and those of the pereion, the former being 

 very long, the latter very short. 



In AmpTiijpoda generally, the segments of the pereion, as a rule, 

 are shorter than those of the pleon, but not to any very great ex- 

 tent in the normal Gammaridce. In the sub -family of the Phoxides 

 we find it more conspicuous, but not so decidedly as in the fossil 

 species. 



Some two years since, I received from a kind and valued corre- 

 spondent (the Eev. George Gordon), among many other specimens 

 from the Moray Firth, an injured individual of an undescribed spe- 

 cies of Amphipod, which I delayed to publish, from a desire of 

 procuring specimens more perfect ; but in this as yet I have been 

 unsuccessful. 



Those parts in the recent specimens, which I presume represent 

 the fossH remains under notice, bear a generic resemblance to them. 



The segments of the pereion, like those in the fossil, are short, 

 while the segments of the anterior portion of the pleon are long. 

 I am thus led to believe that the following description of the recent 

 animal will be found to bear a close generic resemblance to the 

 fossil species. 



The head or cephalon is pointed above, and projects over the an- 

 tennae, the superior of which is short, somewhat pyiiform, the basal 

 articulation of the peduncle being much stouter than, and nearly as 

 long as, the other two. Filamentary appendage short (?) and fur- 

 nished with a complementary appendage, consisting of but a single 

 joint. The inferior antenna, which is placed posteriorly to the 



