062 SUMMARY OF CURRENT RESEARCHES RELATING TO 



branch being continuous with the renal portal and the other with the 

 rectal vein of the hepatic portal. The interest of the variation is the 

 similarity to the conditions obtaining in a Teleostean, where the mesen- 

 teric artery sends a branch to the retc mirabile of the air-bladder, the 

 blood returning to the portal system. The author suggests that the 

 case is one of reversion. 



A Remarkable Axolotl.* — Prof. H. L. Osborn describes an 

 "axolotl" from a low level marsh stream in Dakota. It displays a 

 combination of larval and adult characters in its exterior form. In 

 size it greatly exceeds the average of Ambbj stoma, and its length, 

 312 mm., goes beyond the maximum reported length by 'dO mm. There 

 is a close general resemblance to A. tigrinum, but a decided unlikeness 

 to the hitherto recorded Siredon larva; of that species : — in total size, 

 the shape of the gular fold, the size and shape of the gills, the number, 

 size, and shape of the gill-filaments, the proximity of the eyes to the 

 snout, the coloration of the body, the length of the front limbs, the 

 outline of the post-abdomen, and the locality in which the animal was 

 found. 



Caudal Heart of the Hagfish.t — Dr. C. W. Greene describes the 

 caudal heart in the Californian hagfish, Polistotrema ( = Bdellostnma, 

 Homea) stouti. Eetzius noticed in 1890 a similar paired pulsating 

 organ in the tail of Myxine. Ds function is to drive the blood of the 

 subcutaneous spaces back into the circulatory system. 



Compensatory Movements of the Eyes in Fishes.} — E. P. Lyon 

 finds that certain compensatory eye movements in the dogfish can be 

 produced without the intervention of the semicircular canals. If the 

 tail of a dogfish is turned to one side, the eye of that side is directed 

 forwards, and that of the other side backwards. But as this occurs 

 after the eighth nerves are cut, the reflex does not originate in the ear. 

 As the reflex ceases, however, when the spinal cord is divided well 

 forward in the body, the author concludes that the sensory disturbances 

 which give rise to the reflex arc located in the posterior part of the 

 trunk. This seems inconsistent with Lee's conclusion that the normal 

 compensatory movements of the eye arc reflexes produced by a stimu- 

 lation of the semicircular canals. 



Races of Mackerel.§ — Mr. H. C. Williamson has made a laborious 

 investigation with a view of determining whether racial differences exist 

 between the mackerel of the West and East coasts of Scotland. The 

 methods employed were those used by Heincke in his study of the local 

 forms of the herring. It need hardly be pointed out that the work is 

 of interest in connection with the general problem of variability. 



Of the numerous characters painstakingly measured there are, with 

 three exceptions, probably none which differ in the three groups to an 

 extent that would permit stress to be laid upon them, when the inevitable 

 shortcomings of the dimensions in respect to accurate measurement are 

 taken into account. In the case of the' fin-rays, Unlets, and vertebrae, no 



* Amer. Nat., xxxiv. (1900) pp. 551-G2 (4 figs.). 



t Amer. Journ. Physiol., iv. (1900). See Amer. Nat., xxxiv. (1900) pp. G66-7. 



t Tom. cit., pp. 77-82. See Amer. Nat., xxxiv. (1900) pp. G69-70. 



§ Ann. Rep. Fishery Board for Scotland, xviii. (1900) pp. 294-329 (15 tables); 



