272 LUNG-FISHES x. 4- 



forms lived in fresh water, but *Undina and other Jurassic and Creta- 

 ceous types lived in the sea. 



The first living specimen of the group was fished off the east coast 

 of South Africa and eleven others have since been caught around the 

 Comoro Islands (Madagascar) (Fig. 162). All are referred to the genus 

 Latimeria. They have been caught near the bottom at considerable 

 depths (150-400 m). Unlike most of their fossil ancestors they are 

 large fishes, weighing up to 80 kg; they are dull blue in colour. The 

 whole body is covered with heavy cosmoid scales. 



The notochord is a massive unconstricted rod. The skull possesses 

 a well-marked joint between a condyle on the hind end of the basi- 

 sphenoid and a glenoid cavity on the front of the base of the oto- 

 occipital region. This joint, together with fibrous unions between 

 other bones allows of movement of the front part of the head on the 

 hind. A large pair of muscles runs from the parasphenoid up and 

 back to the pro-otic and serves to raise the front part of the head on 

 the hind. Coraco-mandibular muscles attached to the palato-quadrate 

 have the reverse action and the movement is presumably concerned 

 with catching the prey. There are numerous small teeth on the jaws 

 and palate. Latimeria lives on other fishes, apparently swallowed whole 

 by the powerful oesophagus. There is a well-developed spiral intes- 

 tine. 



The 'air-bladder' arises by a ventral opening from the oesophagus 

 and proceeds backwards and dorsally for the whole length of the 

 abdominal cavity. The lumen is very small and the organ is 95 per 

 cent fat. It may serve to reduce the specific gravity. Respiration is by 

 the gills. The heart shows a linear 'embryonic' condition, with the 

 sinus venosus and auricle behind the ventricle. There are four rows of 

 valves in the conus. The red cells are large, as in elasmobranchs, 

 Dipnoi, and Amphibia. Nothing is known of the development, 

 except that the eggs are large. 



The brain lies far back in the cranium, of which it occupies less 

 than one-hundredth part, the rest being filled with fat. Its structure 

 is somewhat like that of a teleostean, with a thin fore-brain roof, and 

 large striatum, but without eversion. There is no valvula to the cere- 

 bellum. The pituitary cleft is large and the gland remains in continuity 

 with the roof of the mouth. 



There are anterior and posterior nares but both open on the surface 

 of the head and they have nothing to do with respiration. The rostral 

 organ is a large median sac opening to the surface by three pairs of 

 canals and richly innervated by the superficial ophthalmic nerve. 



