MYXINE. 



311 



A small cartilage near the oesophageo-cutaneous duct 

 represents a complex branchial basket found in the lampreys. 

 Lastly, a large lingual cartilage supports the tongue. 



Myxine is unique amongst the Vertebrata in having no 

 trace of vertebrae. 



The coelom is spacious, and consists of a pericardium 

 around the heart 



Coelom. 



FicT 



224. — Ventral Dissection 

 OF Myxine Glutinosa to 

 SHOW the Gill - Pouches 

 X \. {Ad nat.) 



BuccalCirri 



Mouth. 



ventricle. 



Blood- 

 Vascular. 



and an abdominal 

 cavity surrounding the intes- 

 tine which communicates 

 with the exterior by an 

 abdominal pore. 



The heart is like that of 

 a fish. It is two-chambered, 

 with one' auricle and a 

 It lies on the 

 ventral surface 

 of the oesoph- 

 agus, and drives 

 blood by a brajichial artery 

 diverging to the six gill- 

 pouches by six afferent 

 branchials. Six efferent 

 branchials unite dorsally to 

 form a dorsal aorta. These 

 branchials pass between the 

 gill-pouches and each sup- 

 plies blood to the adjacent 

 surfaces of two gill-pouches. 

 The venous system con- 

 sists of paired jugulars and 

 cardinals uniting in a sinus 

 venosus and thence to the 

 heart. 



The brain is small and 

 simple. There are paired 

 cerebral hemi- 

 spheres^ the cere- 

 bellum is very small and the 

 optic nerves do not cross. There are te?i cranial nerves, as 

 in fishes, but there is no sympathetic system. 



Nervous. 



S 



