Prof. Owen’s Description of the Lepidosiren annectens. 343 
Its muscular parietes are very thick, and are formed, not by what are called 
the ‘abdominal muscles’ in 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 membrane ff. This membrane is reflected over the ovaria, which oc- 
cupy the sides of the abdominal cavity; and over the liver$, stomach, and 
intestine|, which are situated between the two ovaria: from the anterior or 
under part of the intestine the two laminæ 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 
anusjf, but within the common cloacal sphincter. The common opening of 
the oviductstt 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 first 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 J, 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 
interspaces of which there is a fine reticulation. 
There was no pancreas, nor pancreatic ceca; neither could any trace of a 
spleen be detected. 
The liver is a flattened subelongate unilobate gland, situated between the 
* Tan. XXIV. fig. 2, n.n. T Ib. fig. 2, m. m. t Tas. XXV. g. § Ib. 4. 
Ib. k. FRE Ib. m. +t Ib. s. 
tt Ib. o. §§ Ib. fig. 3. lll] Ib. fig. 2, d. «€ Ib. e. 
VOL. XVIII. 2z 
