84: Reviews — Memoirs of the American Museum, 



Fritscb to Acrolepis (A. Krejcii, A. spharosideritarunu and A. gigas, 

 Fritseh). The latter is a fine fish considerably more than a metre 

 in length, and the largest known Palaeoniscid ; Dr. Fritseh even 

 suggests that it is the largest known Palaeozoic fish, hut it must 

 have been much surpassed in dimensions both by Iihizodus and by 

 Megalichthys intermedins. A plaster cast of this unique specimen 

 is exhibited in the British Museum (Natural History). 



Some fragmentary specimens bearing much resemblance to 

 Elonichthys aud Rhadinichthys, too imperfect (in our opinion) for 

 generic determination, are regarded as indicating a hitherto unknown 

 genus Pyrogyrolepis, with the single species P. speciosus. This is 

 defined thus : — " Similar to the genus Gyrolepis, but dentition with 

 large pointed teeth, between which are small teeth in irregular 

 rows ; the large teeth smooth at the apex, beautifully striated at the 

 base, with large pulp-cavity ; anterior rays of pectoral and dorsal 

 fins not articulated." 



The name Hemichthys problematical is proposed for a small skull 

 of doubtful relationships, which may even belong to a Labyrin- 

 thodont. A detailed description is promised in the supplement to 

 the next volume. 



In his concluding observations on the Palaeoniscidae, Dr. Fritseh 

 particularly emphasizes the difficulty of regarding the degree of 

 arching of the back as a specific character. He instances the 

 variations in this feature in the common carp, which depend much 

 upon the locality and surroundings. He also adds a warning as to 

 the displacement of the fins by different kinds of crushing. In the 

 head he finds that the cranial bones are thickest when least 

 ornamented ; thinnest and most irregular when the ganoine is best 

 developed. Large otolites appear in at least one species of 

 Amblypterus. With regard to calcified vertebrae, he now considers 

 that his former determination of such elements in the supposed 

 Phanerosteon and Sceletophorus is very doubtful. 



The new part of the " Fauna der Gaskohle " thus equals in 

 interest its predecessors, and bears witness to the same laborious 

 and patient research and attention to minute detail, which 

 characterize the whole of the work. A. S. W. 





III. — Memoirs of the American Museum of Natural History. 

 Vol. I, part 2. August, 1895, pp. 74, plates iv to xiii. 



IN this finely illustrated Monograph Prof. E. P. Whitfield, Curator 

 of palaeontology in the American Museum of Natural History 

 in New York City, gives a second instalment of the republication 

 of descriptions of fossils from the Hall collection, from the Eeport 

 of progress for 1861 of the Geological Survey of Wisconsin, by 

 James Hall. The type specimens, now figured for the first time, 

 are chiefly derived from the Trenton group in Wisconsin. They 

 comprise algae, some of -which were previously confounded with 

 Graptolites, such as the noteworthy Buthograptus laxus, ''an 

 articulated marine form" much resembling the living Caulerpa 

 plumaris of the Florida coasts ; a crinoid, a crustacean (Illaenus 



