54 COMPARATIVE ANATOMY. 



22. Hermaphrodite gland. | 27. Hermaphrodite duct. 



23. Shell. i 28. Yas deferens. 



24. Shield-shaped mantle. 



25. Albuminiparous gland. 



29. Oviduct. 



30. Spermatheca. 



26. Penis. 



Class CEPHALOPODA. 



85. A Cephalopod (Eledone). 



A blue rod has been inserted into the mouth, a red rod into 

 the funnel. 



The body is symmetrical, the organs being arranged sym- 

 metrically with reference to an imaginary vertical plane drawn 

 from before backwards through the centre of the body. The 

 animal is divided into an anterior or cephalic portion, 'pro- 

 soma,' and a posterior, or 'metasoma.' In the centre of the 'pro- 

 soma' and surrounded radially by the arms, is the mouth, and 

 on the opposite sides of it are the sessile eyes. The eight mus- 

 cular arms which surround the mouth correspond to the anterior 

 portion of the foot, 'propodium,' of the Gasteropoda, and are 

 formed by the- extension of the antero-lateral parts of the foot 

 forwards in front of the head, and their union with each other 

 in front of the mouth-: so that this aperture, from its position in 

 front of the anterior margin of the foot, comes to lie in the 

 centre of it. The margins are produced into long muscular 

 processes or arms;, which, in this species, are set with a single 

 row of suckers, by means of which the animal can attach itself 

 to foreign bodies, seize its prey, or move from place to place. 



The 'metasoma/ which contains the chief organs of vegeta- 

 tive life, is invested externally with a thick muscular coat, or 

 mantle. This terminates in front freely, and so allows the 

 entrance of water into the pallia! cavity. On the dorsal surface 

 of the specimen a muscular tube may be seen emerging from 

 the pallial cavity: this is the 'Funnel.' It is formed by an 

 extension of the 'epipodda* upwards, and their subsequent 

 fusion in the medio-dorsal line. The Funnel is broader pos- 

 teriorly than it is anteriorly, and its base is covered by the 

 superior margins of the mantle. 



The Octopoda, to which this species belongs, have no internal 

 skeleton of any kind. The specimen was taken at Algiers. 



