2S 



ferred that they may perform the function of instruments of sensa- 

 tion, and convey the stimulus to contract to the muscular parts 

 that close the outlet of the alimentary canal. In the Octopoda the 

 anus is not similarly provided ; and, indeed, it may be generally re- 

 marked that valvular or other guards are developed among the Ce- 

 phalopoda only in such as have the power of propelling themselves 

 forwards in the water. 



The generative apparatus forming part of the fragments referred 

 to, Mr. Owen examined it with some care. His most important 

 observation relative to these organs relates to a small round flat 

 fleshy body, attached near the anterior aperture of each of the two 

 nidamental glands, destitute of any outlet, and of an orange colour. 

 A single bilobed organ, of a bright orange or red colour, similarly 

 connected with the anterior extremities of the nidamental glands, 

 exists (as was long since pointed out by Swammerdam) in the Cut- 

 tle-fish. In Sepiola the corresponding body is single, and of a rose 

 colour. And there exist two such bodies in a small Cephalopod 

 taken by Capt. Ross on the shore of Boothia, which Mr. Owen has 

 recently described under the name of Rossia palpebrosa. Consider- 

 ing the bright colours which these bodies commonly present, and 

 their structure and relations to the generative apparatus, Mr. Owen 

 feels authorized in regarding them as analogous to the suprarenal 

 bodies, hitherto regarded as peculiar to the Vertebrate series. 



The small Octopus described by Mr. Owen was obtained by Mr. 

 George Bennett, like the Loligo laticeps, among the Sargasso weed; 

 which forms, as it were, a bank in the midst of the ocean, aflFording 

 shelter to many marine animals of littoral genera. The condition 

 of the generative organs would appear to indicate that the specimens 

 brought home were not adult, and the species consequently may be 

 assumed to attain a greater size than that of the largest individual 

 in the collection, which measures only l-j^ inch from the end of the 

 sac to the extremity of the longest arm. Of the eight arms the first, 

 or dorsal, pair is the longest, as is the case in many species of Oc- 

 topus ; the second pair is nearly of the same length as the first ; the 

 third pair (which in the Decapods is commonly the longest) is scarcely 

 half the length of the first ; the fourth pair is nearly two thirds of 

 the length of the first. The musculo-membranous web, which is 

 usually extended between the bases of all the arms in the Octopi, is 

 in this species developed to the ordinary extent between the four 

 dorsal arms only : the webs between the second and third arms, 

 and the third and fourth arms, on each side, are very short ; that 

 between the fourth pair is wanting. From this peculiarity Mr. Owen 

 proposes to name the species Octopus semipalmatus . 



Its anatomy generally agrees with that of Oct. vulgaris. 



The remaining specimens described by Mr. Owen are the shell 

 and animal of Argonauta Mans, Lam. They were obtained in lat. 

 4° S., long. 17° W. The animal was alive at the time of its capture 

 by Mr. George Bennett, but fell out of its shell when it was moved 

 on the following morning. A mass of eggs was then exposed in the 

 involuted portion of the shell, which increased so greatly in size after 



