. The Cephalopoda. Cephalopoda. Oegopsida: Enoploteuthidae vena cava, surround the rectum, then become narrower and pass dorsal to the median ventral luminous organ to the posterior ventral abdominal wall (Plate IV, Figure 18). Brock (1888, p. 22) named these muscles "median pallial adductor1'. I prefer the term "muscular rectus abdominis", because this muscle is not inserted in the membranous septum in the Oegopsida and hardly acts as a mantle retractor; it apparently functions as an abdominal constrictor, like the corresponding muscle of vertebrates. The musculature of the abd
. The Cephalopoda. Cephalopoda. Oegopsida: Enoploteuthidae vena cava, surround the rectum, then become narrower and pass dorsal to the median ventral luminous organ to the posterior ventral abdominal wall (Plate IV, Figure 18). Brock (1888, p. 22) named these muscles "median pallial adductor1'. I prefer the term "muscular rectus abdominis", because this muscle is not inserted in the membranous septum in the Oegopsida and hardly acts as a mantle retractor; it apparently functions as an abdominal constrictor, like the corresponding muscle of vertebrates. The musculature of the abdominal wall partly covers the rectum, so that only its distal part is 66 visible. The anus is bordered by two liplike swellings and bears two well-developed anal appendages, each of which consists of two unusually wide lateral flaps of about equal size, supported by a muscular keel. Comparison with the drawings of the anal appendages of other Cephalopoda by Brock (1880, Plate XII) shows that the large size of the appendages of Thaumatolampas is the starting point for a series of changes the result of which in the Octopoda is that only the keel with weakly developed margin remains. Only the stomach is visible through the abdominal wall. Opening of the abdomen shows that the stomach ends a short distance before the posterior luminous organ and that a shallow groove divides its thick-walled end part from the thin-walled anterior part into which the esophagus enters (Text Figure 20). The caecum of the stomach is situated on the left side, almost at the level of the heart. It is more or less kidney-shaped and slightly laterally compressed; its hoodlike dorsal part is more transparent figure 20. Longitudinal section of posterior half of body of Thuumalolampas: an. anus; , posterior artery; air. ink sac; shell sac; neck cartilage; coll. collar; e. heart; int. intestine: luc. v. large ventral luminous organ; funnel depressor; later
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Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectcephalopoda
