108 BRAIN AND BODY OF FISH 



ranean, are characterised not only by their external features, and by 

 their internal structure, but also by the pattern of their brains. It 

 was fortunate that my acquaintance with P. phycis preceded my 

 knowledge of P. blennioides, as several adaptations rudimentary in 

 the latter are further specialised in the former. The head is larger 

 in P. phycis and the eyes more prominent. In both species the 

 pelvic fin is prolonged on either side by a long filamentous and bifid 

 tentacle ; this seems to be longer in P. blennioides than in P. phycis. 

 Couch describes this fish under the name Greater Forkbeard, or 

 Hake's Dame. It would be interesting to know the origin of this 

 quaint appellation. He says that " these tendrils from their 

 structure may be judged to be endowed with lively powers of sensa- 

 tion ; they have joints along their course and are well supplied with 

 nerves from what may be termed an axillary plexus, situate in the 

 axilla of the fin, one branch of which passes along the course of the 

 fin-rays and sends a branch to penetrate through it, while the other, 

 which anastomoses with the first branch in the axilla, is carried along 

 the posterior margin. Their special function is shown by their 

 proceeding from the spinal cord to their termination, without com- 

 municating with any other nerve ; " this is another example of the 

 careful meticulous detail of the old school of anatomists. 



An interesting point that requires investigation is why the gur- 

 nard should have a paired series of globular swellings in that portion 

 of the cord which receives the nerves from their sensitive filaments, 

 and that the forkbeard has no similar enlargements in its spinal cord. 

 P. blennioides has a range in deiDth of 200-500 fathoms and has been 

 caught in 140 fathoms. According to Hickling it feeds on Crustacea 

 which almost certainly belong to a bottom-fauna, such as crabs, 

 Geryon and Gonoplax, and the prawns, Munidia and Nephrops ; 

 so that there is strong evidence of a bathypelagic habit in this 

 deep-sea fish. 



We have compared the brain of several specimens of P. blen- 

 nioides landed at Milford Haven and compared them with those of 

 P. phycis landed at Funchal. The type in both species is the same. 

 The olfactory lobe and bulb are in close opposition and form a lobe 

 about the same size as the optic lobes. The cerebellum is long 

 but not so long as that of P. phycis ; the medulla oblongata is 

 smallish, and the general appearance is not unlike that of the ling 

 and burbot. The acoustic tubercles are small ; this is of some 

 interest as it suggests that the depth at which this fish lives has not 

 been the cause of any great development of this lobe. We have 

 seen a great enlargement in the acoustic lobes of the deep-sea ling, 

 and it might be thought that its bathypelagic habitat was the cause 



