70 MULLER ON THE MALE OP 



probable ; the ovate or pyriform capsule in the abdomen being 

 similar to that which in Octopus is certainly placed at the free 

 end of the Hectocotylus-arm. 



Besides, both in form and position that abdominal capsule is 

 analogous to the membranous lobe on the appendage of Hecto- 

 cotylus Argonautce. 



Among eighteen Hectocotyli of Tremoctopus, twelve had the 

 abdomen constructed as Kolliker has described it. In six, how- 

 ever, the capsule of the abdomen had a cleft upon its dorsal side ; 

 this commenced close behind the last sucker of the left side (the 

 suckers being supposed to be below and the capsule behind), 

 and extended somewhat obliquely as far as the commencement of 

 the delicate process into which the capsule is prolonged ; the 

 latter lay consequently wide open, and it could readily be seen 

 that it was empty ; that is, that it contained neither the convo- 

 lutions of the seminal capsule nor the ductus deferens, which 

 in other cases are found in the closed capsule*. Upon careful 

 examination, however, the cleft is, even in all ordinary Hecto- 

 cotyli, to be seen as a streak occupying the direction indicated. 

 There is a ridge upon the right side ; pale, more or less closely 

 adherent, and capable of being raised. It can be observed then 

 that the subjacent layer, upon the left side, passes for a cer- 

 tain distance under the other, and appears to be as it were rolled 

 up at its anterior end. 



In Hectocotylus Tremoctopodis this cleft then always exists, 

 and it would be interesting to know whether it also occurs in 

 the capsule of Hectocotylus Octopodis. 



When the cleft is open and the capsule is empty and relaxed, 

 it has a considerable resemblance in external character to the 

 membranous lobe of Hectocotylus Argonautae, which also at 

 times forms a deep pit. Both organs exhibit a lively undulatory 

 movement. 



In order to comprehend more exactly the relative position of 

 the capsule, it is previously necessary to show that the penis of 



* I presume, that at least in most cases the capsule has been burst after the 

 Heclocotyli were taken, by contact with fresh water or the like. In three Hec- 

 tocotyli of the ordinary form which I had thrown into a dilute solution of 

 chromic acid, I also found after a few days the capsule open and the contents 

 fallen out. 



