118 DR. EMBLETON ON THE SHORT SUNFISH. 



size, arranged in one row, guard the auriculo- ventricular orifice. 

 The ventricle is thick, fleshy, and strong, its fleshy columns short and 

 thick. The aortic opening has four semilunar valves, two of which 

 are large, two very small. The buibus arteriosus is small, but fleshy 

 and strong. No opening between the pericardium and the peri- 

 toneum is apparent. The vascular system was not further pursued. 



The nervous system was not examined, but from the second 

 volume of Professor Owen^s Lectures on Comparative Anatomy, we 

 learn that the spinal cord is found " shrunk into a short, conical, 

 and according to Arsaki, gangliated appendage of the encephalon. 

 In the Diodons, which much resemble the Orthragoriscus, there is 

 a long Cauda equina. The cerebellum is an oblong, single, longi- 

 tudinally fissured ganglion, in front of which are a pair of large 

 optic lobes, a much smaller pair of cerebral ganglia, and a minute 

 pair of olfactory lobes supported by slender pedicles. 



When the skin, abdominal muscles, and viscera have been re- 

 moved, the body presents two broad compressed masses, the head 

 and the trunk, united by a very narrow isthmus, the upper part 

 of the spine. The dorsal muscles, separated on the median line 

 by a thin ligament um nuchas, arise from the occiput and from a 

 fibrous membrane attached to the side of the bodies of the verte- 

 brae, and which runs down as far as the posterior part of the 

 abdominal cavity, beyond this the muscular bundles arise from 

 the upper half of the bodies of the vertebrae, and from the neural 

 spines and interspinous bones. These muscles all converge to- 

 wards the base of the dorsal fin; the vertebral, which overlap the 

 occipital bundles, are inserted upon a series of strong tendons, 

 which go to be attached to the fin rays j the occipital mass of 

 fibres passes backwards and is partly inserted upon the vertebrae, 

 and partly upon the series of tendons of the fin rays just men- 

 tioned. The muscles for the anal fin arise from the lower half of 

 the bodies of the vertebrae behind the abdomen, and from the 

 hoemal spines and interspinous bones, and converge to be inserted 

 upon a series of tendons attached to the rays of the anal fin. 

 Small short muscular bundles pass backwards from the bodies 

 and processes of the posterior vertebrae, diverging to the different 

 portions of the caudal fin. The abdominal muscles are thin. 



