| OCR Text |
Show 1892.] BODY-CAVITY. IN SNAKES. 489 § V. Explanation of the List of Snakes given in § III. a-signifies a Snake in which I have clearly found the full complement of peritoneal spaces as described above, § IV., viz.: - a. The posterior peritoneal space. /3. The paired liver-sacs. y. The gastric sac of left side. <5. The " omental " space. b-signifies a Snake in which I have not clearly made out the " omental" space, though all the others occur ; but * indicates that this probably is present. „ I „ „ possibly c-signifies a Snake in which I have not clearly made out either of the smaller peritoneal spaces, i. e. either the " gastric " or the " omental," though the principal sacs, viz. the two liver-sacs and the posterior peritoneal space, occur. t indicates that a Snake probably has a " gastric " sac. tt „ ,, „ possibly i - Typhlops.-In this the anterior and posterior boundaries of the gastric sac were not clearly made out. 2-Bryophis (one of the long " W h i p Snakes " ) . - I cannot pretend to have seen the posterior boundary of tbe liver-sacs, but have no reason to believe that they are not closed as in all other cases. 3-Lamprophis.-It is possible that the right testis is enclosed in a separate peritoneal sac apart from tbe posterior peritoneal space. If so, this would be a peculiarity of this Snake. 4 - Vipera nasicornis.-I a m not sure that the gastric sac does not communicate with the posterior peritoneal space. If it does, we merely have a persistence of a condition of things which (see § VI.) certainly does persist to a comparatively late embryonic stage. The list in § III. in part speaks for itself. I may point out, however, that Snakes marked b and c are essentially similar as to the relations of their peritoneum to those marked a. The "gastric" and still more the " omental" space is as a rule small, and anyone who did not know exactly where to look for either would in most cases not find them. Where there was no clear indication of one or both, I have marked the Snakes b or c as explained ; and it is quite possible that one or both of them may be found in Snakes so marked. Moreover, even if they are absent this does not indicate any hard-and- fast dissimilarity between the Snakes marked b and c and those marked a, for development (§ VI.) shows that both the " gastric " and the " omental" spaces are, with rare exceptions, but reduced remnants of original more extensive ones; and a comparative study of the Snakes on the list shows that when these spaces are present, the amount of reduction of either varies very greatly, not only in different species but in different individuals of the same species. It is not then surprising, but, rather, just what we should expect, that in some cases one or both of these spaces should have become obliterated altogether. |
