INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 873 



1. There appears to be complete ideutity of properties between 

 tbe muscles of the lobster and those of the frog. 



2. The motor nerves of the lobster present, from a physiological 

 point of view, strong points of resemblance with those of the frog. 

 The most characteristic difference consists in the slowness with 

 which the motor excitation travels along the lobster's motor 

 nerves (6 metres a second in the lobster, 27 metres in the frog). 

 The propagation of the motor excitation undergoes, in the lobster, a 

 considerable retardation in the muscular terminations of the motor 



Action of Electric Currents on the Pincer of the Crayfish.* — 

 By the aid of the graphic method, and the slowness with which the 

 muscles of the piucer elfect their contraction, M. Kichet has been 

 able to show that the form of the muscle-wave varies with the intensity 

 of the electric currents which effect it ; it is short when the currents 

 are feeble, although longer than in the muscles of the frog. When 

 the intensity of the cxxrrent is increased the form alone changes ; the 

 fall of the curve is at lirst rapid and then gradually slackens. As the 

 current is increased in intensity the second period increases in length, 

 and the former diminishes until at last it may be seen to completely 

 disappear ; and it follows from this that it is not the height but the 

 duration of the muscular contraction which increases with the increased 

 intensity of the exciting currents. That the contraction is due to 

 change in the muscle itself, so far, at any rate, as its second portion 

 (that of gradual relaxation) is concerned, is shown by the fact that 

 this " contracture," as the author calls it, is barely apj)arent when the 

 motor nerve is itself directly excited. The myographic traces ob- 

 tained were found to be remarkably similar to those exhibited by 

 muscles poisoned by veratrin. These observations may bo taken 

 as supplementary to those previously recorded. | 



Atlantic Stalk-eyed Crustaceans.^ — Mr. S. J. Smith, of Yale 

 College, publishes an account of the stalk-eyed crustaceans of the 

 Atlantic coast of North America. It forms part of the report in pre 

 paration for the United States Commission of Fisheries, and embodies 

 the study of the extensive collections made during the past fourteen 

 years by Professor Verrill and himself. 



In the present paper only the species inhabiting the coast between 

 Cape Cod and Northern Labrador are given, and although the paper 

 has special reference to the geographical distribution of the species, 

 considerable matter is introduced in regard to specific variation and 

 specific characters, and under some of the species, to the synonymy, 

 especially where it seemed necessary to the proper understanding of 

 the geographical distribution, or to show the propriety of the nomen- 

 clature adopted, or where the species is not well known. 



* ' Comptes Eendus,' Ixxxviii. (1879) p. 1272. 

 t This Journal, ante, p. 562. 



X 'Traus. Connecticut Acad. Arts and Sci.,' v. (1879); 'Nature' xx. (1879) 

 p. 535. 



