628 LECTURE XXIV. 



the place of the external labial process, there was a conoid process 

 2^ inches long, also formed of four tentacular sheaths, one of which 

 was shorter and terminated freely, the other three remained confluent 

 to the end of the process : it occupied much of the space included by 

 the external circle of tentacular sheaths. 



The male Argonaut has an analogous modification of the tentacular 

 system, indicative of its sex. Not any of the cephalic arms are sail- 

 shaped, but one of them is longer and much thicker than the rest, 

 and its double series of suckers are longer and more numerous.* In 

 the female Argonaut {fig- 220.), two of the arms develope the broad 

 and thin membranes, which form, repair, and usually overlap the 

 delicate nidamental shell f, which is peculiar to this sex.| In the 

 Calamary (Loligo vulgaris), the gladius of the male is one- fourth 

 shorter, but is broader than that of the female. The sepium of the 

 Cuttle ( Sepia) shows a similar, but not so much sexual, difference in 

 its proportions. In the Dibranchiates the male organs consist of a 

 testis, a vas deferens, a vesicula seminalis, a prostate, the sac of the 

 spermatophora, and the penis. 



The testis is situated in a particular compartment of the perito- 

 neum at the bottom of the visceral cavity ; that membrane being 

 reflected over it, from one point, to form its serous capsule : it is 

 simple, roundish or oblong, and consists of a fibro-membranous pouch 

 (^fig. 229, a a), to one part of the inner surface of which are attached 

 a number of slender branched tubuli {b), diverging, dichotomising, 

 and terminating in blind extremities : the tubuli swell at the breeding 

 season, burst, and discharge an opaque white fluid, crowded with 

 spermatozoa, into the cavity of the sac, whence it escapes by a con- 

 .tracted orifice (c) into the slender and convoluted vas deferens (d), 

 where the fluid is moulded, by the addition of a mucous secretion, 

 into a cylindrical coherent mass. In this state it is transmitted to a 

 wider glandular canal (e), having fibrous parietes and a cellular cavity 

 in Octopus, and being encroached upon, in Sepia, by a plicated produc- 

 tion of the lining membrane : this division of the efferent part of the 

 male apparatus answers to the glandular part of the oviduct in the 

 female : here the spermatozoa are enclosed in filamentary sheaths of 

 albuminous matter, of a definite form, according to the species of 

 Cephalopod. The anterior extremity of this contractile vesicula 

 communicates, in Octopus, with a wide, bent, csscal tube (prostate,/), 

 with thick glandular parietes, and having the form of a simple pouch 

 in Sepia, from which a short and wide duct leads to a longer and 

 larger pyriform pouch, " Bursa Needhamii," or spermatophorous sac 



* CCCCIX. and CCCCX. f CCCCVIII. t CCCXCVIII. 



