RAMBLES OF A GEOLOGIST. 287 



tail of the lobster ; for which, by the way, they were mis- 

 taken by the workman who first laid the fossil open. I ex- 

 amined, too, with some interest, fragments of a gigantic spe- 

 cies of Pterichthys, belonging to an inferior division of the 

 same Upper Old Ked formation as the yellow stone, desig- 

 nated by Agassiz Pterichthys major, which must have attain- 

 ed to at least thrice the size, linearly, of even its bulkier con- 

 geners of the Lower formation of the Coccosteus. After ex- 

 amining many a drawer, stored, from the deposits of the neigh- 

 bourhood, with characteristic fossils of the Lias, the Weald, 

 and the Oolite, and of the Upper and Lower Old Red, we set 

 out together to expatiate amid the treasures of the Town 

 Museum. 



Among other recent additions to the Museum, there is 

 an interesting set of the fishes of the Ganges, the donation 

 of a gentleman long resident in India, to which Mr Duff call- 

 ed my attention, as illustrative, in some of the specimens, of 

 the more characteristic ichthyolites of the Old Red Sandstone. 

 One numerous family, the Pimelodi, abundantly represented 

 in the Gangetic region, in not only the rivers, but also the 

 ponds, tanks, and estuaries of the district, is certainly worthy 

 the careful study of the geologist. It approaches nearer, in 

 some of its more strongly-marked genera, to the Coccosteus 

 of the Lower Old Red, than any other tribe of existing fishes 

 which I have yet seen. The body of the Pimelodus, from 

 the anterior dorsal downwards, is as naked as that of the eel ; 

 whereas the head, and in several of the species the back, is 

 armed with strong plates of naked bone, curiously fretted, as 

 in many of the ichthyolites of the Lower, and more especially 

 of the Upper Old Red Sandstone, into ridges of confluent 

 tubercles, that radiate from the centre to the edges of the 

 plates. The dorsal plate, too, when detached, as in many of 

 the species, from the plates of the head, bears upon its inner 

 side a strong central ridge, that deepens as it descends, till 



