454 SUMMARY OF CURRENT RESEARCHES RELATING TO 



are very large ; the fibres passing from their nuclei to the tectum are 

 strongly developed. The commissura ansulata and decussatio transversa 

 seem stronger than in other Amphibia. There is no cerebellum. A 

 unique bundle extends over the middle line at the caudal end of the roof 

 of the mesencephalon, probably representing a crossing of the cerebellar 

 nerve-tracts isolated by the absence of the cerebellum. 



The degeneracy of the optic apparatus is associated with the cave 

 life ; the strong development of other sensory tracts is a compensatory 

 hypertrophy ; the absence of cerebellum is associated with the sluggish 

 mode of life. 



Sailing Fishes.*— Louis Dollo discusses what Brousonnet called 

 " poissons voilier," that is to say fishes that use the dorsal fin as a sail. 

 This is said to be true of Histiophorus. Dollo argues that it is also true 

 of Plagyodus, which is not abyssal, as is generally supposed, but pelagic. 

 It is probable that GetorMnus and Orthagoriscus are in the same position. 

 It is possible, Dollo thinks, that Orca and Globicephalus are " sailing " 

 Cetaceans, just as Velella and Physalia are " sailing " Siphonophora. 



Story of Devil-Fish.f— Theodore Gill contributes one of his 

 interesting studies on fishes, his subject being what are called devil- 

 fishes. The name has been widely used, but the author restricts it to a 

 family of ray-like Selachians, variously known as Cephalopterida?, Ptero- 

 cephalicte, Mobulids, and Mantidge. They are the largest and widest 

 of rays, and have horn-like extensions on each side of the head. They 

 inhabit warm seas and feed chiefly on small crustaceans and young or 

 small fishes. Normally there is a single young one at a birth. 



Removal of Swim-bladder in Minnow.}— J. Giaja removed the 

 swim-bladder from a number of specimens of Phoxinus Isevis, and found 

 that disturbances resulted somewhat like those observed by Gouriet and 

 Bonnier in the carp. The minnows moved as if with more effort than 

 usual, rose often to the surface, and kept the body curved with the 

 caudal part hanging down. But they did not lose their balance as the 

 carp did. At the end of six months two which had been operated on 

 were indistinguishable from their uninjured neighbours, but there was 

 no regeneration. 



Fishes of Illinois.§— S. A. Forbes and R. E. Richardson have in a 

 handsome and beautifully illustrated volume furnished a reliable guide 

 to a knowledge of the fishes of Illinois. This includes an account of 

 their local and general distribution, and of their relations to their 

 environment. The authors give careful descriptions of 150 species 

 based on personal observation, and they discuss the habits and utilities 

 of the fishes and their importance in the general system of aquatic life. 



* Zool. Jahrb., xxvii. (1909) pp. 419-38 (2 figs.). 



t Smithsonian Misc. Collections, lii. (1909) pp. 155-80 (16 figs.). 



X G.R. Soc. Biol. Paris, lxv. (1908) pp. 125-6. 



§ The Pishes of Illinois : Natural History Survey of Illinois. Published by 

 authority of the State Legislature, 1908, exxxi. and 357 pp. ; numerous col. pis., 

 with an atlas of 103 maps showing the distribution. 



