of British Mollusca. 483 



The left ventral arm of the male is hectocotylized as 

 described under the genus ; but in this species a further modi- 

 fication takes place in the fact that the normal suckers at the 

 base of the arm are smaller in size than the corresponding- 

 suckers of the right ventral arm. 



Specimens in my collection are from Jersey (Si net) } Tenby 

 (C. Jeffcry), Plymouth (Biol. Lab.). I have also found it 

 in Lamlash Bay, Firth of Clyde. North Wales (Hoyle). It 

 has been found in many other places on our southern coasts, 

 but it becomes scarce northwards. 



Distribution. In consequence of this species being so fre- 

 quently confounded with the preceding I hesitate to quote 

 records of its occurrence. It is not without much doubt that 

 I have kept them distinct; but judging from the specimens 

 1 here record they appear to be so. 



B. S e p i o p h u A. 



Section 2. KATOPROSTHARSENIA. 



Fam. 6. Sepiidse. 



Genus Sepia., Linne*. 



18. Sepia officinalis, Linn. 



The distribution of this species is West Africa, Mediter- 

 ranean, Spain, France, British Islands (chiefly southern coasts), 

 Sweden (Norway ?) *. 



Hectocotylization takes place in Sepia on the lower portion 

 of the fourth or ventral arm. In S. vulgaris it is the left arm 

 which is thus affected. It is widened out near the base, only 

 two or three suckers in each row are at the origin of the 

 arm normally developed, whilst the seven or eight following 

 suckers in each row become very small or almost evanescent ; 

 the arm, widened much at this part, has the muscles 

 developed in a peculiar manner, " becoming elevated, lying 

 like oblique beams across the arm, and partially crossing 

 amongst themselves, by which means a number of pits are 

 formed, which are especially deep towards tiie upper margin. 

 Lastly, in these pits and on the portions which separate them 

 the skin is everywhere folded into elevated, thin, membranous 

 laminae which run together into a reticulated form and give 

 the whole surface of this part of the arm a certain resem- 

 blance to the inside of a calf's stomach." (Stecnstrup.) 



* Fischer makes tbe Mediterranean form a distinct species from the 

 northern, and names it »S'. Filiouxii (see Journ. Conch, xviii., xx., xxi., 

 xxii.). If that he so, the more southern localities here quoted probably 

 belong to that species. 



