ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 601 



they live, is not quite warranted. P. Regnard made in 1891 precise 

 thermo-electric experiments which showed that fresh-water fishes have 

 to a fiftieth of a degree the same temperature as the water in which they 

 live. But J. Pavey found that some marine fishes are warmer than the 

 surrounding water, — in Pelamidesby 7 "22°, and in the Bonito by 10°. 



Portier took the temperatures of numerous tunnies (Thynnus alalonga) 

 just as they came out of the sea, and found that these powerful swimmers, 

 which can keep up for hours with a vessel going at twelve knots, show 

 (on deck) rectal temperatures of 21 • 5°, temperatures at the level of the 

 liver of l ( J , G°-24°, and temperatures in the middle of the dorsal 

 muscular mass of 25 , 5°-26'7°. The last was "J* 2° higher than that of 

 the surrounding water. 



Unilateral Coloration with Bilateral Effect.* — C. H. Eigenmann 

 and Clarence Kennedy describe two specimens of a Leptocephalid, 

 probably of the same species {Lqtiocephalus dvptychus). Each has eight 

 large black spots, one over the intestine somewhat in front of the anus, 

 the others on the two sides of the body. Each spot was a single giant 

 chromatophore, extending longitudinally over three or four somites. 

 The peculiar fact was that the spots are unsymmetrical, those of one side 

 alternating with those of the other, so that in the almost transparent 

 animal there seemed to be seven spots at approximately equal distances.. 

 The authors regard this as a case of " mutual adaptation." 



Variations of Garter Snakes. f — E. E. Brown has studied the 

 variations of Butcmia in the Pacific sub-region, from about latitude 50° 

 in British Columbia to the neighbourhood of 33° in southern California- 

 There is a great variety of soil and climate, especially as regards 

 humidity : thus the rainfall'at Puget Sound has reached 130 inches, while 

 at Yuma, in south-eastern California, the average is little more than 

 three. Under these circumstances, and having in mind the ease with 

 which colour in reptiles is acted upon by external conditions, of which 

 there is reason to believe that moisture is one of the most active, it is 

 not surprising that colour variation should reach a maximum in a group 

 of snakes which, through diversity of habit, occupy practically every 

 station open to their kind. The author reduces 23 alleged species to 

 three, two of which have three sub-species. He suggests (1) that 

 humidity influences the metabolic processes which lead to pigmentation ; 

 (2) that the large amount of uric acid produced by reptiles should be 

 considered in connection with coloration ; and (3) that the liberty to 

 indulge in striking colours may be associated with the protection afforded 

 by the luxuriant vegetation and with the absence of the three snake- 

 eating genera, Spelotes, Ophibolus, and Elaps. 



American Pelycosauria.J — E. C. Case has re-examined the American 

 types and has been led to conclusions very different from those of Cope. 

 All known reptiles from the American Permian, other than the Cotylo- 

 sauria, possessed two temporal arches ; there is no approach to a single 

 temporal arch as described by Cope in some of them. The Pelycosauria 

 followed a line of development that led to extinction, Avhile the persist- 



* Science, xiii. pp. 82S-80. See Zool. Zentralbl.. x. (190:1) pp. 504-?. 



t Proc. Acad. Sci. Philadelphia, 1903, pp. 286-97. 



X Amer. Naturalist, xxxvii. (1903) pp. 85-102 (10 figs.). 



