Dr. A. Giintlier on Sexual Differences in Frogs and Fishes. 377 



We find in the British specimens both stylospores and asci. 

 The latter, however, are not sufficiently perfect to contain fnll- 

 grown sporidia. The stylospores are exactly like those figured in 

 the ' Horticultural Journal.-' As regards the sporidia, we nuist 

 wait for better information. The genus, at any rate, is new to 

 this country. 



[To be continued.] 



XXXVIII. — On Sexual Differences found in Bones of some Recent 

 and Fossil Species of Frogs and Fishes. By Dr. Albert 



GUNTHER. 



[With two Plates.] 



The production of the following paper has been induced by an 

 examination of several fossil remains of Batrachians in the Col- 

 lection of the British IMuseum ; they were procured near Lagoa 

 Santa (Brazd), in localities containing remains of those fossil 

 South American mammals which have been described by Lund, 

 Owen, Gervais, &c., and arc unequivocally in a truly fossil state. 

 Nevertheless I am induced to believe, from comparison with the 

 skeletons of living species, that the fossil remains which I shall 

 here discuss do not belong to species different from the recent. 

 Being unaware of the existence of any description of the ske- 

 letons either of the fossil or living animals, I thhik it the more 

 necessary to give one, as we shall find a new proof how important 

 is the knowledge of sexual differences existing in the osteology 

 of living species, in many instances of determining fossil remains. 



There are, first, two skulls, in a more or less perfect condition, 

 and two fragments of maxillary bones. Although differing in 

 form, and still more in size, they both belong to the same spe- 

 cies, Ceratophrijs cornuta. I have compared them with the male 

 and female of their descendants of our period, and have found 

 that the latter present exactly the same differences in the struc- 

 ture of the head. 



The skull of Ceratophrys is distinguished by its complete 

 ossification, by its excessively firm structure, by the tubercular 

 sm-face of all the upper parts, and by the extraordinary develop- 

 ment of bones belonging to the dermo-skeleton, surrounding the 

 eye and forming an orbit, externally completely closed : nearly 

 all the sutures seem to disappear in early age. 



The skull, which I believe to be that of a male Ceratophrys 

 cornuta^ (PI. XV. fig. A), is broadest between the articular ex- 



* For comparison with Ceratophrys ornata, see the figure given by 

 Hallowell, Journ. Nat. Sc. Ac. Philacl. 4th series, vol. iii. pi. 36, under the 

 name of Triyonophrys ruyosa. There is another figure on the same plate 

 (right-hand, bottom), probably representing a restored skull of Ceratophrys 

 cornuta ; but there is no reference whatever to it in the text. 



