178 



PTEROPODA. 



They consist, first, of an Ovary with its 

 oviduct; secondly of the "bladder;" and, 

 thirdly, of the testis, upon which the bladder 

 rests. 



The ovary (Jig. 113. 27, p) is closely con- 

 nected with the liver, in conjunction with which 

 it occupies the dorsal region of the abdominal 

 cavity, its anterior part being filled with the 

 voluminous testicle. The ovary itself is nearly 

 of a hemispherical shape, and is of a pale red 

 colour, its surface having a granular appear- 

 ance. When crushed under the microscope, 

 all the granules of which it consists exhibit 

 in their interior a little vesicle, together with a 

 dark spot ; the former being, doubtless, the 

 vesicle of Purkinje, the latter the germinal 

 spot of Wagner. 



The oviduct (</) is tolerably thick, and 

 arises from the middle of the flat surface of 

 the ovary ; it immediately becomes consider- 

 ably convoluted, so that it usually forms two 

 loops, and, gradually becoming attenuated, 

 reaches the " bladder " (s) y which is situated 

 in immediate contact with the testicle; but, 

 before joining the latter, it generally swells 

 into a dilatation (/) ; but this dilatation is not 

 constant ; for sometimes Eschricht found two 

 such enlargements ; whilst in other instances 

 the ovidijct retained the same diameter 

 throughout its entire length : when present, 

 the swelling was found to be solid, and pro- 

 bably was produced by an accumulation of 

 ova, coagulated by the action of the spirit in 

 which the specimens had been preserved. 



The " bladder " (s) is situated very close 

 to the surface of the testis, and appears to be 

 supported upon a furcate stem, through the 

 intervention of which it is partly in communi- 

 cation with the oviduct, and partly with the 

 testicle. This " bladder " is somewhat larger 

 than the accidental swellings of the oviduct 

 alluded to above, but, like them, was found to 

 be solid ; and sometimes the mass was divisible 

 into two flattened halves, a circumstance that 

 would seem to indicate the non-existence of 

 any cavity in the interior. 



The testis itself, in a recent specimen, is so 

 large as to occupy a very considerable part of 

 the abdominal cavity: it is nearly transparent ; 

 and when portions of it are examined under 

 the microscope, its substance seems to be en- 

 tirely made up of minute tubes, connected to- 

 gether by delicate membranous processes. Its 

 external convex surface (Jig. 113. 28) is convo- 

 luted, so as to give it the appearance of being 

 a hollow vesicle three times folded upon itself; 

 whilst its inferior concave surface exhibits 

 under the microscope a reticulate appearance, 

 something like that of the stomach of a ru- 

 minant quadruped. 



The common outlet of the ovary, of the 

 bladder, and of the testicle is short, but toler- 

 ably thick. It mounts upwards, and ter- 

 minates close behind the right fin, in the im- 

 mediate vicinity of the anal orifice. 



On opening the cavity of the head, by re- 

 moving its anterior wall (including the collar 

 and the subjacent muscular layer), its contents 

 are displayed as exhibited in Jig. 111. 16. Im- 



)end- 



mediately behind the contracted conical app 

 ages, and close to their hollow bases, is seen 

 a long milk-white organ (b), which, in old 

 specimens, is so extremely brittle, that it is 

 generally broken in the dissection. Behind 

 this, and close to the collar, lies a red sac- 

 culus not easily to be displayed ; and, in the 

 neck itself, immediately upon the collar, is 

 situated a single loop, formed of the same 

 white substance as b. 



On carefully unfolding these parts, they are 

 found to present the structure displayed in 

 fig. 113. 26, the transverse body (b) and the 

 loop (c) constituting portions of the same 

 viscus. The transverse portion is a canal 

 terminating by a blind extremity (a), while 

 the loop itself may be displayed as an ex- 

 tremely attenuated canal (d) of a reddish 

 colour, which, after several convolutions, opens 

 into the red sacculus (g), and ultimately ter- 

 minates in another short, but wider, tube (/) ; 

 the common orifice of the sacculus and of 

 the convoluted canal is a wide, longitudinal 

 opening, situated in the cavity between the 

 right fin, the head, and the collar. On cutting 

 into this canal, it is found that the milky 

 colour it presents is but slightly owing to the 

 nature of its contents, depending principally 

 upon the texture of its walls, which, when ex- 

 amined under the microscope, are found to 

 contain numerous granular bodies, which are 

 apparently of a glandular character, united to- 

 gether by a very thin and transparent mem- 

 brane,, the delicacy of which readily accounts 

 for the fragility of the tube. 



The structure of the red sacculus (g) is 

 not yet fully understood. Its walls are in 

 some parts very thin, and on opening it, the 

 tube (/) is seen to be continued through it. 



Eschricht was, at first, in considerable doubt 

 as to the nature of this remarkable apparatus : 

 he observed, however, that in several speci- 

 mens, a portion of the sacculus was inverted 

 and protruded externally in the shape of a long 

 bow-shaped organ (Jig. 114. 3,^), along the 

 cavity of which a delicate canal could be 

 distinctly traced, the bow-shaped organ being 

 manifestly the penis, everted in the same way 

 as in many Gasteropod Mollusks, and the de- 

 licate canal constituting the vas deferens. 



HVALEA. The two fins are supported 

 upon a fleshy neck, enclosed between the two 

 lobes of the mantle (Jig. 1 14. 3, c), which latter 

 (fig. 1 14. 3, g, h, i, k} correspond accurately 

 with the valves of the shell, beyond the edges of 

 which they protrude all around, and which 

 they cover with a thin epidermis. 



The position of the branchiae Cuvier ob- 

 served not to correspond with what he had, 

 erroneously, believed it to be in Clio, namely, 

 the surface of the lateral fins ; for in Hyalea 

 he could not discover any vascular net-work 

 in those organs, even with a microscope ; and 

 thus indirectly confirms the correctness of 

 Eschricht's views upon this point. He, there- 

 fore, sought for them elsewhere, and, " on 

 breaking the shell, he found them to be situ- 

 ated between the two lobes of the mantle at 

 the bottom of the outer space between them 



