Prof. Owen's Description of the Lepidosiron annectens. 343 



Its muscular parietes are very tliick, and are formed, not by what are called 

 the ' abdominal muscles' ivi the higher vertebrates, but by the lateral series of 

 oblique muscular fasciculi. The proper tunic of the abdomen is a strong 

 glistening fibrous membrane*, which is lined by a delicate and transparent 

 serous membranef. Tiiis membrane is reflected over the ovaria;}:, which oc- 

 cupy the sides of the abdominal cavity; and over the liver '^, stomach, and 

 intestine II, which are situated between the two ovaria: from the anterior or 

 under part of the intestine the two lamintç of the peritoneum are continued 

 in a straight line, forming a kind of mediastinum^ to the opposite parietes of 

 the abdomen, which is thus divided into two lateral compartments in the two 

 posterior thirds of its extent: these compartments gradually contract poste- 

 riorly into peritoneal canals, which intercommunicate by an oval aperture 

 three lines in length, and have a common external outlet** in front of the 

 anusft, but within the common cloacal sphincter. The common opening of 

 the oviducts :{;| is behind the anus. 



The lungs §§ and kidneys are entirely posterior to the peritoneum. 



The intestine is three inches and a half in length, and becomes gradually 

 contracted to the vent; it is traversed throughout by a spiral valve ||||, which 

 performs six gyrations : the extent of intestine traversed by the tirst turn is 

 the greatest, measuring above an inch : the second is suddenly shorter, being 

 about four lines in length : the remaining folds gradually diminish to three 

 lines in longitudinal extent. The valve terminates by forming' a longitudinal 

 ridge in the narrow rectum ^^, which measures about an inch in length. 

 The tunics of the intestine are thick and strong, especially the internal one, 

 which presents a glandular structure similar to that in the Sturgeon : its sur- 

 face is, however, proportionally less strongly honeycombed: it is increased 

 at the beginning of the intestine principally by spiral linear elevations, in the 

 niterspaces of which there is a fine reticulation. 



There was no pancreas, nor pancreatic cseca ; neither could any trace of a 

 spleen be detected. 



The liver is a flattened subelongate unilobate gland, situated between the 



* Tab. XXIV. fig. 2, n.n. \ lb. fig. 2, m. m. % Tab. XXV. g. § lb. h. 



II lb. k. *\ lb. /. ** lb. m. tf lb. n. 



XX lb. 0. §§ lb. fig. 3. nil lb. fig. 2, d. ^11 lb. e. 

 VOL. XVIII. 2 z 



