224 Reviews — Dentition of Ptycltodus. 



Eifel, Germany, a spine of Heteracanthus uddeni from Iowa, and the 

 upper dentition of the Arthrodiran Dinognathus ferox from Ohio. 

 Carboniferous species are numerous, but for the most part very 

 fragmentary. A new species of the peculiar spine, Harpacanthus, 

 from the St. Louis Limestone, Missouri, is noteworthy. Triassic 

 fishes are well represented in the Museum, and fragments of trunk 

 from the Kanab Valley, Utah, are referred to a new species of 

 Lepidotus, named L. walcotti,. after their discoverer. The Jurassic 

 and Cretaceous fishes are scarcely noticed, but a supposed new species 

 of Notagogus is figured from the Lithographic Stone of Bavaria. 

 Photographs of several Tertiary fishes are published, including 

 Parafundulus nevadensis, gen. et sp. nov., from the Lahontan Beds, 

 Nevada, and Ameiarus primcevus, sp. nov., and Priscacara dartona, 

 sp. nov., both from the Green Biver Shales of AVyoming. 



X. — Dentition of Ptychodus. 

 Dkscrizione di tjn notevole esemplare di Ptychodus, Agassiz, 



TROVATO NEL CALCAEE BIANCO DELIA CrETA SUPERIORE DI GaLLIO 



nei Sette Comuni (Veneto). By Professor Mario Canavari. 



Palaaontographia Italica, vol. xxii, pp. 35-102, pis. v-xiv, 1916. 

 rPHE natural arrangement of the teeth of Ptychodus in the jaw was 

 1 first shown by specimens from the English Chalk, and next by 

 a fine example of P. mortoni from the Chalk of Kansas, U.S.A. 

 An unusually well-preserved dentition of both jaws has now been 

 found in the Upper Senonian of Northern Italy, and is described in 

 a beautifully illustrated exhaustive memoir by Professor Canavari. 



The Italian specimen, which belongs to the variable group 

 commonly known as P. polygyrus and is regarded as representing 

 a new form or species, P. mediterraneus, must have originally 

 comprised about 1,090 teeth in the two jaws. It shows the usual 

 median row of diminutive teeth in one jaw, the relatively large 

 median teeth in the other, and there seem to have been nine paired 

 rows of teeth in each jaw. The former dentition measures at least 

 47 cm. in length by 44 cm. in breadth, while the latter measures at 

 least 50 cm. by 42 cm. Professor Canavari thinks that the second 

 would form a dental armature almost flat transversely, while the first 

 would be gently arched from side to side. He therefore concludes 

 that Dr. Smith Woodward was probably wrong in his determination 

 of the upper and lower jaws of Ptychodus, and proposes to reverse 

 them. Unfortunately, however, the supporting cartilages are only 

 represented by fragments, so that the new specimen does not settle 

 the question conclusively. 



XI. — The Atlantic Slope Argas. By Pearl G. Shicldon. Palseonto- 

 graphica Americana, i. pp. 100, with 16 plates. 



WE welcome this, the first number of a new publication, edited 

 by the energetic Professor Gilbert D. Harris, of Cornell 

 University. The memoir deals with the Becent and Tertiary species 

 of the Lamellibranch Area, found on the east coast of North America," 

 and includes mention of Cretaceous species from elsewhere and of 



