230 



In the head of the Coelacanth quite massive bones lie right in the 

 surface. The skull itself is not a single unit as in most fishes, but is in 

 two almost separate parts across behind the eyes. The brain cavity is 

 quite a reasonable size. There are no nostrils like those of modern 

 fishes, but in the cartilage in the front of the head before the eyes is a 

 peculiar central and quite large cavity, from which six tubes lead to the 

 surface, two to the front and two to each side of the head in front of the 

 eye. At first sight, externally, one might think the two openings on each 

 side to be nostrils, like those of modern fishes, but they are not, and 

 up to the present no one has been able to say exactly what this structure 

 is. When my account of the first Coelacanth was published, the 

 description of this particular part puzzled all scientists, and one went 

 as far as to say that I must have been mistaken. The very first thing I 

 looked for in Malania was this structure, and, sure enough, there it was, 

 exactly the same. It was also the first thing Nielsen looked for in 

 Malania. He told me, apologetically, that they all had doubted my 

 description and figure. We scratched our heads together. 



Most bony fishes have a well-developed soft *air bladder', which 

 lies above the intestines in the body cavity. (It was mentioned on p. 92 

 that when a trawl-net comes up, the fall in pressure causes the air- 

 bladders of the fishes to expand.) The modern Coelacanth has no true 

 air-bladder. In some fossils there is a peculiar structure in the belly 

 cavity in the position in which the air-bladder is generally found, but 

 in those earlier Coelacanths this was 'calcified', i.e. it had hardened 

 walls. It has been assumed, therefore, that Coelacanths had air-bladders, 

 but that these had become hardened. An air-bladder is apparently used 

 to adjust the average density of a fish to suit its environment, or else 

 as a breathing organ. What use an air-bladder with hard walls would 

 be it is difficult to imagine, but in some existing fishes there has been 

 found a degree of calcification of their air-bladders. At any rate, 

 there is no true air-bladder in the modern Coelacanth, only a shred of 

 skin that may be the remnant of an air-bladder that might once have 

 been present. It may be mentioned that sharks and rays have no air- 

 bladder. 



In the Coelacanth the gills are not soft cartilage like modern fishes, 

 but bony and hard. They bear teeth and not ordinary soft gill-rakers. 



The scales of the Coelacanth are both peculiar and characteristic. 

 The main basal part is almost horny and with less bone than a com- 

 parable modern fish. The 'tubercles' on the scales are separate units, 

 each set on its own little plate, and each is hollow. The scales overlap 

 so much that the whole body has a covering three scales thick, a power- 

 ful protective armour. 



While the Coelacanth has bony jaws and powerful jaw muscles, the 



