268 XEW YORK STATE MUSEUM 



In Gasteropoda, as well as in Cephalopoda, Crustacea and 

 Arachnida the function of respiration is brought about by an 

 albuminoid substance analogous to hemoglobin, but containing 

 copper instead of iron, this substance, which Fredericq names 

 haemocyanin, forming a. very unstable combination. 



The saline matter contained in the blood of the Helix is 

 about 1.075fo; in L i m a x about 1.115;^. 



Touching the color of the blood, Mac Munn^ says in regard to 

 the blood of H e 1 i x p o m a t i a : "It assumes a distinct blue tint 

 on exposure to 'the air, and gave no absorption bands, but ab- 

 sorbed a little of the violet end of the spectrum. On, treatment 

 with ammonia its color ^'as not sO' well marked, and it had a 

 partially reddish tinge, but no bands oould be seen, and after, 

 treatment with acetic acid did not remove the color." 



One time I drowned 12 individuals of P. a 1 b o 1 a b r i s, 

 leaving them, as usual, in the water about 48 hours. The blood 

 in the arteries of all these specimens had coagulated and turned 

 a dark purple black in color, so that the course of the arteries 

 could be as distinctly traced as if they had been injected. I am 

 unable to account for this phenomenon, as of scores of specimens, 

 treated in the same manner, these were the only specimens 

 coagulated and colored, though the others were kept in the same 

 box and fed on the same kind of food. 



Kervous system 



The nervous system (pi. 12) consists of five distinct sets of 

 ganglia, and four ganglionic swellings, and the commissures con- 

 necting them or proceeding from them. The principal ganglia 

 are the supra-esophageal^ the infra-esophageal, consisting of two 

 sets, and the two buccal ganglia. The ganglionic swellings, or 

 ganglia, are situated at the extremity of the tentacles. The 

 ganglia corresponding to the one situated on the dorsal surface 

 of the stomach inLimax maximus I have not observed in 

 P 1 y g y r a. 



When the animal is extended, the supra-esophageal ganglia 

 are situated just above the esophagus, immediately posterior to 



1 Quart, jour, micro, sci. 1885 



