Introduction to A uiuial JMorphology. ^i^ 



fibres pass forwards (fibres of Langer) to the origin of the 

 iris, which is a circular fold in front of the lens, also contain- 

 ing a support-cartilage within it. Within this is an argeiitea 

 interna, and the retina. The front of the choroid is thickened 

 into a corpus ciliare {c. epitheliale), developed from the anterior 

 lining cells of the primitive optic vesicle, which surrounds 

 equatorially, and is continuous with, the biconvex lens whose 

 hinder surface is the more convex. Behind the lens is a 

 fluid vitreous humour. The retina consists of two layers, an 

 outer {stratum conjtuictivuni) and an inner {s. epitheliale). These 

 consist of seven lamina, the outer of four"^' and the inner of 

 three. f There is neither lens nor cornea in Nautilus, and 

 the eye chamber is an open cup, as it is in the earliest stage 

 in the embryo of Dibranchs. There is no cornea in Loli- 

 gopsis nor Histioteuthis, and in Loligo there is a hole in the 

 cornea, whereby the sea-water bathes the front of the lens. 



The lobate, unsymmetrical ovary dehisces into a 

 segment of the perivisceral space, from whence its 

 products enter the usually azygous genital ducts 

 (paired in Octopodidae, Ommastrephes). The oviduct 

 opens at the beginning of the funnel, or in forms with 

 hectocotylized males, deeper in the mantle cavity. 

 The oviduct wall has an annular gland in Nautilus 

 and Octopods, and near its mouth a pairof rudimental 

 glands, long lamellar pouches, secrete the sheath for 

 its eggs. 



The testis has a capsule which, like that of the 

 ovary, is only attached to it at one spot; its vas 

 deferens is long, coiled, widening to its end, often 

 with one or two prostatic appendages, or a coiled 

 caecal pouch. The papillary opening of the vas has 



* ]Membrana limitans, or surface connective, nerve vesicles, and a reti- 

 cular or connective support layer. 



t A pigment layer containing rods, granules, a layer of rods and an 

 inner limiting homogeneous layer. 



Y2 



