142 OCTOPIDJE. 



boat on the lower part, and forming an abruptly denned and 

 regular hood at the base : apopliysis crest-shaped, not project- 

 ing beyond the base, consisting of a slight and sharp ridge for 

 about a quarter of an inch at the back, and elevated at the 

 base into an irregular and jagged prominence, which in some 

 specimens extends to the top of the cartilaginous hood. L. 2-5. 

 B. 0-9. 



HABITAT : Polperro (Laughrin) ; shells only on sandy 

 beaches at Mawgan Porth in Cornwall, and Oxwich 

 Bay near Swansea (J. G. J.), Guernsey (F. C. Lukis), 

 Northumberland (Alder), and Magilligan in Derry 

 county (Hyndman). It has consequently a rather 

 extensive range. North-west of France (D'Orbigny 

 pere and others); Mediterranean and Adriatic (Philippi 

 and Verany). 



It appears to be the 8. elegans of Ferussac and D'Or- 

 bigny (but not of De Blainville), and perhaps also their 

 S. rupellaria, as well as the S. rubens of Philippi. 



B. OCTO'CERA, De Blainville. Octopoda, Leach. 



Mantle globular or oval, symmetrical, and usually not ex- 

 panded on either side : the ventral portion is small in compa- 

 rison with the rest of the body : arms 8, webbed at the base ; 

 suckers sessile, not pedunculated, nor having a horny ring : 

 gills attached by the stalk only. 



SHELL none, except in the genus Argonauta, where (in the 

 female only) it is external and forms a single involute chamber. 



Family III. OCTO'PIME, D'Orbigny. 



Mantle attached to the neck, without fins or lateral expan- 

 sions. 



