British Marine Testaceous Molhisca. 479 



connection by their habitudes, the position of their eyes, and 

 .other points of structure, is so close to the PyramidelUdse, that 

 ^ey may without violence precede and be associated with that 

 family, which consists of very numerous species, all having eyes 

 at their mesial or internal bases, with short triangular tentacula, 

 and by our present method of a lateral branch springing from 

 Conovulus are naturally brought together. In like manner the 

 Trochidse, Skeneadse and Turritellidse, all of which have circuiaj- 

 opercula, except Phasianella pullus, which however is undoubt- 

 edly of the trochidan tribe, follow the Littorinidse, and with them 

 are part of the components of another lateral branch, and are 

 thus linked together without an invasion of natural position. 

 The newly constituted family of the Peloridse, with its genera 

 Scalaria, lanthina, Natica, Lamellaria and Velutina, are so largely 

 mentioned in the descriptive notes of their respective species as 

 to render further remark unnecessary. The same observation 

 applies to the Muricidse and Cyprseadse, which terminate the Bri- 

 tish testaceous MoUusca. 



'*^^ ^ Sixth Division. 



_* '^ Cephalopoda dibranchiata. 



afjX Bisexual. 



These singular and highly organized animals are distributed 

 in two families : the Octopodidse include the genera Eledona and 

 Octopus ; the Decapodid£e, Loligo, Sepia, Sepiola and Spirula : 

 they all creep and swim. They are elaborately and anatomically 

 described and illustrated by M. Cuvier in his memoirs, and by 

 Professor Owen in the second part of the second vol. of the 

 * Zoological Transactions.^ We have merely mentioned these 

 animals to preserve intact the chain of the synopsis. To attempt 

 to add novelty to this almost exhausted subject would be a vain 

 and fruitless labour. 



I have now finished a limited analysis of my method of the 

 distribution of the British marine testaceous MoUusca. I am 

 led to think the sexual arrangement natural and well-founded, 

 as it cannot fail to have been observed that as the generative in- 

 fluences are more or less perfect, there is a corresponding energy 

 and activity. If we cast a glance at the strict hermaphrodites, as 

 the Acephala and Patella tribes, we find them either fixed or of 

 the most limited locomotion ; but as soon as the generative struc- 

 ture is improved, the animals become more lively and locomotive. 

 This view is exemplified in the hermaphrodites with congression, 

 for instance, in the natatory Gasteropoda and Pulmonifera ; but 

 when bisexuality is established, there is an evident increase of 

 motion, functions, and I may say, even of intelligence and struc- 



