80 Trail mctionii. — Zoology. 



Circulatory Organs.— Hem we have the purely typical 

 Teleostean type. The only peculiarity and difference between 

 Lotella and Gadus that I have been able to make out is 

 that in Lotella the 3rd and 4th efferent branchial arteries 

 unite and form a common trunk before opening into the left 

 epibranchial artery. 



Organs of Respiration. — The gills are four in number, and 

 conform to the Teleostean type. 



There is, however, also a rudimentary gill. This pseudo- 

 branchia is seen as a small red patch covered with mem- 

 brane and lying just under the operculum. Thus it is a little 

 anterior to the dorsal end of the first branchial arch. On 

 removing the membrane we see a rather irregular red body, 

 usually with marked indications of a filamentous structure 

 (fig. 4). But in some specimens examined absolutely no trace 

 of filaments could be made out. In all cases, however, the 

 blood-vessels to the pseudobranchs could be made out. 



Brain. — Again we have a structure almost identical with 

 that of Gadus morrlma. 



I have noticed in all the specimens I examined a very thin 

 cord of nervous matter passing, on each side, along the 

 brain-membranes, and slightly dorsal to the brain. This 

 cord unites the tenth nerve with the cutaneous branch of the 

 fifth. 



The so-called prosencephala have no trace of a cavity, 

 and it seems perfectly justifiable, as stated by Eabl- 

 Riickarat, to consider them as merely elevations on the 

 floor of the prosencephala, the roof of which is formed by 

 pia, and which is consequently very easily torn away, and 

 is so in usual dissections of the brain. The microscopic 

 anatomy seems to me to put all doubt out of the question. 

 The brains were hardened in situ, the bone decalcified, and 

 sections made. In these sections (figs. 16 and 20) the 

 pallium or roof of the prosencephala was well shown. 



Auditory Organ (figs. 5 to 9). — The auditory organ con- 

 sists of an ovoidal vestibule (i'.) and three semicircular 

 canals— two vertical and one horizontal. The vertical canals 

 are anterior and posterior. Each canal starts from the top of 

 the ovoidal vestibule with a swollen part — the ampulla — and 

 passes upwards to the dorsal region of the auditory capsule. 

 They then pass backwards and forwards respectively, and 

 finally meet. Their adjacent limbs are thus confluent. The 

 common limb then passes directl}' downwards, and opens into 

 a swelling at the top of the vestibule. The horizontal canal 

 [h.s.c.) hes entirely on the outer side of the vestibule, and 

 opens into it by two separate openings. The ampullte of the 

 canals are situated at their extreme ends, those of the 

 anterior and horizontal canals being anterior, and that of the 



