THE HAKE AND THE SCABBARD FISH 



117 



On removing the roof of the bony cranium, it is found that the 

 brain is well supported by a thick tenacious nnicus, so that it is ad- 

 visable to harden the brain, before endeavouring to separate it from 

 the enveloping mucus. The brains of all the Trichiuridse hitherto 

 examined, Plate 23, which include the white scabbard fish, the rabbit- 

 fish (Promethicthys prometheus), and Nesiarchus nasutus, conform 

 to the same type, and recall the type seen in the hake. The optic 

 lobes are relatively not large, the cerebellum small, and not tongue- 

 shaped, bearing on its lateral margins globular projections, which 

 are the acoustic tubercles, more prominent than in the hake. The 

 somatic -sensory lobes are well-marked, but the medulla oblongata 

 does not show any differentiation into lobes posterior to these 

 prominences. 



PLATE 23. 



Aphanopus Lepidopus Promethichthys Nesiarchus 



carbo. caudatus. prometheus. nasutus. 



PEB— Primitive end-brain. OL— Optic lobe. CLM— Cerebellum. 

 ALL — Acoustico-lateral lobe. SSL — Somatic-sensory lobe. 



The primitive end-brain is globular, of moderate size, and is 

 prolonged anteriorly into smaller olfactory bulbs. Another deep 

 sea fish which I was able to examine was the sea-bream, Brama rail, 

 which also belongs to the Scombriformes, a stout fish with a deep 

 body which descends to over 200 fathoms. On removing its brain 

 it was at once evident that further confirmation of the view was 

 present, that excessive prominence of the acoustic tubercle was 

 associated with a deep water habitat. 



The brain of this fish is characterised by a larger optic lobe, and a 

 larger cerebellum than in the scabbard fishes, while the acoustic 

 tubercles though prominent are not so globular. Brama is a pelagic 

 and predatory fish and is often to be seen in the Maderia fish market. 



The white-scabbard fish is of similar shape as the black, but is 

 remarkable for its uniform silvery appearance ; it may grow to a 

 length of six feet. According to Norman this is a surface fish, but 

 my informant, ]Mr. Gunther Mohl, the curator of the Museum at 

 Funchal, told me that it is sometimes caught at 100 fathoms, and 



