OCTOPUS. 109 



Family I. OCTOPHhE. 



Genus OCTOPUS, Cuvier. 



1. The cups of the arms sub-equal, regular. 



A . The lower cups far apart, in one series. 



a. Body smooth, not bearded. 



b. Body smooth, bearded. 



c. Back slightly granular. 



d. Back granular, rough. 



B. The lower cups rather crowded. 



a. Body smooth, not bearded. 



b. Body smooth, bearded. 



c. Body minutely granular. 



d. Body granular, rough. 



2. The cups of the dorsal pair of arms largest. 



3. The seventh to the twentieth cups of the lateral (second and third) 



pairs of arms much larger than the rest. 



4. Doubtful and apocryphal species. 



The foregoing synopsis is founded on that of Gray, (Brit. Mus. 

 Cat. Cephalopoda Antepedia, 1849), and his arrangement of the 

 species is generally followed by me. D'Orbigny groups the 

 species according to the relative length of the arms which 

 grouping I have adopted for their more minute discrimination. 

 The dorsal arms are considered the first pair, the laterals the 

 second and third pairs, and the ventrals the fourth pair ; they 

 are numbered 1, 2, 3 and 4 in these pages. An attentive study of 

 numerous specimens convinces me that there is much variation 

 between individuals of the same species in all the discriminative 

 characters above indicated, and that these are therefore far from 

 constituting as perfect a scheme of classification as could be 

 wished. A large number of species have been described without 

 figures, and (especially by Gray) from single individuals pre- 

 served in alcohol ; these w&y be all considered as very doubtful, 

 and I hazard little in predicting that many of them will be 

 found, upon careful comparison, to be mere synonyms. In 

 different individuals of the same species I have found several 

 different series of comparative lengths of the arms, the lower 

 cups either far apart or crowded, the body either smooth or 

 granulated. Owing also to the contraction, distortion and 

 rigidity acquired by alcoholic specimens, measurements cannot be 

 depended on. I have found no other discriminative characters 



