OCR Text |
Show 1890.] HELODERMA SUSPECTUM. 197 While in New Mexico, several years ago, I collected a large series of Phrynosoma douglassii, and I have an alcoholic specimen of one of these before me at the present time. Upon opening it I find that the greater part of its peritoneum, posteriorly, is deeply pigmented (almost or quite black), while it lacks the horizontal membrane dividing the coelom, and so agrees with the Iguana- Lacerta group as pointed out by Beddard1. The liver of this Phrynosoma is very thin and broad, spreading out nearly across the abdominal cavity. Its left lobe is considerably the larger and the thinner ; it extends well behind and laterally covering, for the most part, the neighbouring viscera. I find its gall-bladder subspherical in form, with very thin coats, while in the arrangement of its duct (for there is but one of them) and the hepatic duct it agrees with what T. J. Parker found in Lacerta viridis-that is, a " common bile-duct, running parallel to the portal vein and opening posteriorly into the duodenum : at its anterior end it is formed by the union of the cystic duct and the hepatic duct from the liver itself" 2. Judging, then, from Professor W . N. Parker's figure of the Frog, we may have (1) several ducts leafling from the lobes of the liver, and combining in a single duct that goes to the gall-bladder; (2) a duct from the gall-bladder to the pancreas; (3) a duct from the liver to the pancreas ; (4) the proper hepatic ducts combining to form one that enters the pancreas and in it join a duct traversing that gland ; (5) a common biliary-pancreatic duct passing from the end of the pancreas to the duodenum. Judging from Beddard's description of Varanus salvator, we may have in that lizard:-(1) at least three ducts leading from the liver to the gall-bladder ; (2) at least two proper hepatic ducts that unite before joining the common duct; (3) a cysto-hepatic duct that joins the cystic duct-a final union, posteriorly, with a single cystic duct and an hepatic duct to form the common duct; (4) an interlacement of cystic ducts upon the surface of the gall-bladder. The relations with the pancreas are not given by the writer quoted. Judging from T. J. Parker's description of Lacerta viridis, we may have simply the cystic duct uniting with the hepatic duct to form the ductus communis choledochus which opens into the duodenum. Judging from what we find in Heloderma, we may have :-(1) a cystic duct uniting with an hepatic duct to form a single duct that opens into the duodenum ; (2) proper hepatic ducts that pass to the pancreas, usually two that unite in a single one before coming to that gland; (3) a common duct from the pancreas to the duodenum: 1 Proc. Zool. Soc. 1888, p. 100. I a m inclined to think that this character is going to prove to be of no little value in the study of the structure of Lizards in future researches. 2 Parker, T. J., ' A Course of Instruction in Zootomy (Vertebrates),' 1884, p. 165. According to Owen, " In the Iguana there is a distinct hepatic duct which enters the duodenum about an inch from the pylorus, a cyst-hepatic duct which enters the side of the gall-bladder, and cystic ducts which leave the globose bladder abruptly " (loc. cit. p. 451). |