1892.] BODY-CAVITY IN SNAKES. 479 



criticism, is absolutely incorrect and misleading when he says of the 

 Boa constrictor, " es ist kein Cavum thoracis oder abdominis vorhan- 

 den. . . ." ; for tiie peritoneal cavity ("cavum abdominis ") with its 

 various subdivisions, judging by a young specimen in the British 

 Museum, which, by the courtesy of Mr. Boulenger, I was permitted to 

 examine, is better seen in Boa constrictor than in most Snakes. It 

 is, however, hardly surprisin;; that anyone, not forewarned by allied 

 studies, should err as to the peritoneum of these animals. 



I shall notice the paper by Lataste and Blanchard presently. 



We are also referred to F. Leydig [■' Ueber die einheiniischen 

 Schlangen," Senckenberg. naturf. Gesellschaft, Band xiii. 1883-4]. 

 Leydig, however, like the writer in the ' Thierreichs,' who is 

 perhaps following him, quotes indiscriminately Herring, who is 

 wrong, and Retzius who is right ; and the conclusion which {loc. cit. 

 p. 214) he says we may draw from the various descriptions (as to 

 the coexistence of a peritoneal cavity and a subdivided lymph-space) 

 is, as might be expected, vague, and does not convey a correct idea 

 of the actual facts. 



To one who has elsewhere found nothing but incomplete and 

 usually very meagre and general, if not incorrect, accounts of the 

 Ophidian peritoneum, it is a pleasure to turn to the account of 

 Retzius (1) & (2). 



This author in 1830 described the state of things in the Python, 

 overlooking no division of the peritoneal cavity ; though in the case 

 of two of the smaller spaces he simply calls them " serous canals." 

 His description of the peritoneum appears to be as complete as it is 

 possible for such a description of the anatomical features of any one 

 animal to be, without the light thrown by comparative anatomy and 

 development. One small division of the peritoneal cavity, which 

 embryology shows to be a remnant of the "omental" space, I did 

 not myself discover in any adult Snake until after reading Retzius' 

 account of the Python. But although this careful " old master " 

 seems to have seen more than any one else since, I nevertheless hope 

 that there will be something " new " in the following paper, in so far 

 as a study of their mode of origin furnishes material for the discussion 

 of the true nature and the homologies of the various peritoneal 

 spaces, and in so far as a comparative study of examples of nearly 

 all the families of Snakes enables me to state it as probable 

 that most, if not all Snakes, while differing considerably in other 

 respects, are essentially alike in their peritoneal cavities ^ 



We come now to the papers by Lataste and Blanchard (3) and 

 Blanchard (4). The statement on p. 95 of (3), to the effect that 

 the peritoneum does not extend anteriorly to the gall-bladder, is 

 qualified by one on p. 106, to the effect that there are two serous 



^ For instance, Tupinambis {Tejus) differs strikingly from other Lizards in 

 the possession of a most distinct transverse septum behind the liver (see Proc. 

 Zool. Soc. 1889, plate xlviii. and text). I have recently discovered a previous 

 mention of this structure by Meckel [Deutsches Archiv fiir die Physiologie 

 (Halle), Band iii. 1817, p. 218J. However, Meckel gave no figure or detailed 

 description of this septum. 



33* 



