310 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



rectus pelvis, which are all represented in Selachians, and those muscles 

 of the exitus which owe their origin to the musculature of the hind 

 limbs. The smooth musculature is also dealt with. J. A. T. 



Mating in Frog-s.— Harold CmnimQ^ {Joiini. Exper. ZooL, 1920, 

 30, 825-43). Migration of frogs (of four species) into a pond at the 

 breeding time occurs in waves, during periods of high relative humidity 

 coincident with temperature ranging between about 41° and 52'' Fahr. 

 Voice does not direct the movements of frogs into the pond ; sight is 

 not essential for correct coupling and seems unimportant in sex recog- 

 nition. Sex "recognition" in clasping results from the differential 

 behaviour of the two sexes when clasped, and depends on the reaction of 

 the clasping male to this differential behaviour. Clasped normal males 

 struggle, inflate the vocal sacs and croak, and are always released. 



J. A. T. 



Diemyctylus viridescens with Bifurcated Tail.— Bertram: G. 

 Smith (Report Michigan Acad. Sci., 1918, 15, 105, 1 fig.). A specimen 

 with the tail forked in a vertical plane, each ramus of the forked portion 

 having a distinct vertebral column and spinal cord. In the ventral 

 ramus the spinal cord is not continuous with that of the dorsal ramus, 

 but is perhaps connected with it by nerve fibres. In ordinary spina 

 bifida the tail is divided in a horizontal plane. The condition of the- 

 specimen is probably due to an injurv, followed by regeneration. 



J. A. T. 



Toxicity of Extract of Eel.— G. Buglia {Atti Soc. Tosccma Sci. 

 Nat., 1919, 32, 165-98, 2 pis.). Aqueous extract of the cutis of young 

 stages of Anguilla has a toxic influence like that of the blood serum. 

 The same is true of the fluid secretion of the skin in the same juvenile 

 stages, while the larva is still transparent. J. A. T. 



Spiracular Sense-Organ in Fishes.— H. W. Norris and Sally P. 

 Hughes (Anat. Record, 1920, 18, 205-9, 1 fig.). Various investigators 

 have called attention to a sense-organ in the spiracular cleft of Elasmo- 

 brancbs and Ganoids, which is probably homologous with Pinkus' organ 

 in Dipnoi. The structures are derivatives of the lateral line system 

 of sense-organs. The writers find on the anterior mesial wall of the 

 spiracular cleft of Squalm acanthias, both embryo and adult, a tubular 

 organ Avhich bears one or more sense-organs. It is very variable in 

 form and structure. In the most differentiated condition a small pore 

 in the spiracular wall leads into a sac-like expansion with which are con- 

 nected three diverticula, two short and cup-like and the third much 

 elongate. The entire organ with its three diverticula evidently re}>resents 

 a much modified ampulla of Lorenzini. Its occurrence in Mustelus is 

 noted. In Raia radiata a diverticular sense-organ opens not into the 

 spiracle, but on the roof of the pharynx at the anterior border of the 

 inner pharyngeal opening of tlie hyomandil)nlar cleft. J. A. T. 



Fish Food in the Limfjord.— P. Boyhen Jensen {Rep. Danish 

 Biol Station, 1920, 26, 1-44, 4 charts). The stock of bottom animals, 



