2*76 A. E. Yerrill — North American Cephalopods. 



eter. The under surfaces of the fins, siphon, head, and ai*ms have 

 fewer and smaller spots, and are, therefore, lighter colored, and 

 appear nearly white when these spots are contracted, 



A fresh specimen, caught in Casco Bay, in 1873, had the following 

 proportions: Length of head and body, not including the arms, 

 221™'" ; length of caudal fin, 86 ; breadth of fin, 90 ; diameter of body, 

 35; length of upper arms, 80; of second pair, 100; of third pair, 

 100; of the ventral pair, 90; of tentacular-arms, 182""'". 



Of our species, I have measured large numbers of specimens, pre- 

 served in diiferent ways, and also fresh, and have found no great vari- 

 ation in the form and relativ e length of the caudal fin, among speci- 

 mens of similar size and in similar states of preservation, nor do the 

 sexes differ in this respect. The young, however, differ very de- 

 cidedly from the large specimens in these respects. The modes of 

 preservation also cause much of the variation in the proportions of 

 fins and arms to the mantle. The two sexes are probably equally 

 numerous, but in our collections the females usually predominate, and 

 the largest siDCcimens are usually females, though equally large males 

 occur. In 31 measured specimens, in alcohol, from various localities 

 and of both sexes, the average length, from tip of tail to dorsal 

 edge of the mantle, was 176""" (6*96 inches); from tip of tail to inser- 

 tion of fin, 66"'" (2*60 inches) ; average proportion of fin to mantle- 

 length, 1:2-68. Among these the proportions varied from as low as 

 1 : 2'48, in some of the larger ones (with mantle above 8 inches), up to 

 1 : 3-00, in the smaller ones (with the mantle less than 3 inches long). 



The following tables are intended to illustrate the natural varia- 

 tion in the proportions, due mainly to age, and the accidental varia- 

 tions caused by differences in the modes of preservation and strength 

 of the alcohol. 



The specimens from Eastport, Me., designated G. H. I. R., were 

 collected at one time, in midsummer, and preserved in the same way, 

 in alcohol of moderate strength, repeatedly changed ; at the present 

 time the strength of the alcohol is about 80 per cent. They are in 

 good condition, moderately firm and not badly contracted. Those 

 designated as D. E. F. N. O. P., were also collected at one time, in 

 August, and preserved together. They are in fair condition, but not 

 so well preserved as the former lot. Those numbered ii to xiv 

 were preserved together, about the last of July. They were placed 

 in strong alcohol and are hard and badly contracted. J. K. and L. 

 were preserved together, but were originally found dead on the beach 

 and in a relaxed state. They are only moderately contracted by 

 the alcohol. 



