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Show 1890.] HELODERMA SUSPECTUM. 193 we have just said. In the submedian, longitudinal plane it constitutes the umbilical ligament, and this double fold of membrane partially divides the coelom into right and left halves. Of unusual size, the corpora adiposa here lie between the internal muscular parietes and the peritoneal layers, while the kidneys are external to the latter, the reproductive glands internal to it, the two being separated by the horizontal portion of this membrane. Following the peritoneum to its attachments we find it to be fast all along the spinal column, while ventrally it is firmly attached mesio-longitu-dinally to the muscular wall of the coelom. The parietal layer also makes fast to the tendino-fascial divisions, here and there, that indicate the lines of insertions of the digitations of the principal body-wall muscles. Other than this, both the visceral and parietal layers of the peritoneum in this Lizard are but loosely attached to the parts they cover, and may by gentle traction be easily detached. Thoracic and abdominal cavities are partitioned from each other by the usual reflection of this membrane, while below the liver the large anterior abdominal vein is seen to be borne in the ventro-parietal layer. Continued as the umbilical ligament, it passes between the lobes of the liver as a single layer, which in our present subject bears the ramifications of a large vein. Beddard has called the visceral layer of the peritoneum, as it occurs in certain Lizards, the " horizontal membrane;" and this author, in a masterly paper upon this subject (P. Z. S. 1888, p. 99), has said that " In Monitor there is some little difference (from Iguana and Lacerta) ; when the body-walls are cut open and reflected, the alimentary viscera are not exposed as they are in Iguana. A loose membrane covers these viscera; the membrane looks as if it were simply the lining peritoneum of the abdominal cavity which had got separated and detached from the abdominal parietes ; this is, however, not the case ; an examination by the aid of the microscope showed clearly that a layer of peritoneum covers the abdominal musculature, and is quite distinct from the horizontal membrane ; in Varanus griseus the peritoneal layer was particularly distinct, for the reason that it contained numerous pigmented corpuscles. For the greater part this membrane is free from the ventral parietes ; anteriorly it is attached to the median ventral line ; dorsally it is attached along the spinal column; here and there it is also attached to the lateral parietes by membranous bands. It passes over the lobes of the liver and the stomach, and shuts off the lungs from the abdominal cavity. The umbilical ligament dividing the two liver-lobes is present as in Iguana, and is attached to the dorsal side of the horizontal membrane. This horizontal membrane also separates the kidneys from the reproductive glands ; the latter lie internally to it; the kidneys are placed outside it. The ventral surface of this membrane bears a vein of some size, the anterior abdominal vein. The fat-body, when present, lies below the membrane, and is therefore shut off from the abdominal cavity." In many forms, and Beddard gives us a list of some of them (Lacerta, Uromastix, Cgclodus, Iguana, and others), this horizontal membrane is for the greater |