INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 927 



ventral portion of the renal sac into two lateral regions ; the right 

 one is elongated in form, and save for its urethral opening would 

 ajjpear to be closed. It extends backwards as far as the aboral 

 surface of the branchial heart, while anteriorly it gradually diminishes 

 in size, as it passes into the right ureter. The right ventral portion 

 is almost completely filled up by the numerous api^endages attached 

 to the veins which traverse it ; these are, when fresh, more or less 

 transparent and liyaline, and of a spongy texture, they vary in size, 

 and in s^iirit specimens often form a single mass. 



The author then enters into a detailed account of the veins of this 

 (riglit ventral) region. In it, as in the left ventral portion, there are 

 (l)a branch of the vena cava, (•2) the lateral pallial vein, and (8) the 

 vena abdominalis ; and these are attached to the dorsal and lateral walls. 

 But in the left half there is not, as there is in the right, any vein for 

 the ink-bag, or any vena genitalis ; but instead of these there is a me- 

 senteric vein. The left half is, moreover, not so completely closed as 

 the right is, for there is a pore by means of which it is connected 

 witli the dorsal half of the renal sac. There are, further, communi- 

 cations (two) between the two ventral portions. The superior or 

 d(n"sal portion of the sac is a spacious cavity which, save for the 

 already-mentioned ventral pores, is completely closed ; but it does not 

 lie directly qu the ventral half, for it is separated by a portion of the 

 body-cavity, of a considerable size. Various digestive organs are to 

 be found within it ; there is the spirally coiled cfecura, and the two 

 gall-ducts, with tlieir peculiar ajjpeudagcs, to which the name of 

 pancreas has been a])plied. The intervening body-cavity, already 

 mentioned, is connected with the sac by two orifices ; near tlie base of 

 each ureter there is, on the inner wall of the sac, an orifice which leads 

 into a canal ; this canal widens into a cavity, in which there is con- 

 tained the asymmetrically placed arterial heart ; the hinder portion 

 of this "pericardial cavity" is occupied inferiorly by the ink-baf' 

 and the generative organs, and is limited superiorly by the dorsal 

 portion of the renal sac; its right side is almost completely filled up 

 l)y the stomach. This then may be known as the viscero-iJcricardial 

 cavity. 



Within the renal sac there are to be found reddish spheres with a 

 sharp contour, and not rarely surrounded by a colourless ring ; there 

 are also rhombic crystals, sometimes reddish in colour, and varyin" 

 much in size ; in form they resemble crystals of uric acid, and they 

 seem undoubtedly to be products of excretion. Other spheres are 

 also to be seen in the freshly killed animal, which are of a pale green 

 colour, and generally exhibit a concentric structure; it is possible 

 that these are developiiieutal stages of the true excretion-spheres. 

 The wall of the sac is made up (d' fibrillar connective tissue, with a 

 few muscular bands. Tlio inner surface is invested by a unilaminato 

 mosaic of ejiithelial cells, fiattened or polygonal in form, and pi*ovidcd 

 with largo nuclei. In the ureter there is a (.•ylindricul epitlieliuni, 

 whicli gives rise to a fine cuticle; on the opjiosite side of tlie basal 

 membrane tliero arc a nunilna- of irregularly arranged, circular and 

 longitudinal muscular fibres. Tlie venous appendages ai)pear to liave 



3 Q 2 



