118 Part III. — Tiuenty-sixth Annual Report 



Argenteus. — The swim-bladder ends at the vertebra in front of the 

 first haemal arch. The first and second arches are filled with 

 the kidney, which ends at the 3rd arch. 



Saida. — The swim-bladder ends a little in front of the first haemal 

 arch ; the kidney ends at the first hae nal arch. 



TJie Form of the Abdominal Cavity. — In some cases the first haemal 

 spine ends the abdominal cavity, e,g., callarias, fig. 91 ; seglefinus, fig. 81 ; 

 virens, fig. 74 ; poutassou, fig. 70. In other species the cavity is con- 

 tinued posterior to that point, either above it, that is, into the haemal 

 arches, or below, into a sub-haemal cavity formed between the haemal 

 spines and the interspinous bones of the first anal fin. 



Of the former condition the following si)ecies are examples : — Pollachius, 

 fig, 72; luscus, fig. 71; minutus, fig, 80; esmarki, fig. 75; argenteus, 

 fig. 69. In these fishes the liver, ovary, and gut may extend into the 

 haemal arches. The fishes which have the sub-haemal extension of the 

 abdominal cavity are merlangus, fig. 62, and saida, fig. 60. None of the 

 movable abdominal organs enter the haemal arches, but they have room 

 below for expansion. Poutassou, in which the haemal spines are markedly 

 bent backwards, fig. 70, might be regarded as having a slight sub-haemal 

 extension. 



In many of these 'fishes the interspinous region of the first anal has a 

 long stretch which is not directly supported by the vertebral column. 



The peritoneum is loosely attached to the hind end of the abdominal 

 cavity. 



In esmarki a white matter of a soft and fatty appearance was found 

 in the haemal arches. 



In saida the abdominal cavity is lofty, the vertebral column coming 

 very near the dorsal edge. 



The Shape of the Siuim-hladder. — In the Gadids the swim-bladder is 

 usually large. The anterior end is sometimes famished with horn-like 

 prolongations. 



In callarias these are long and they have a spiral form. They pass 

 round the head kidney and lie on top of it, between the branches of the 

 vagus nerve and the muscles at the top of the clavicle. 



Pollachius, fig. 85 ; merlangus, fig. 95 ; and virens, have two short 

 horns. In one virens the horns were absent. 



According to Kolreuter, the swim-bladder in navaga has two horns. 



XXI. Urinary Bladder : — 



The urinary bladder has two 



lobes ...callarias, ogac, aeglefinus, minutus, 



esmarki, argenteus, (saida). In 

 argenteus the lobes are short. In 

 saida one or two small swellings 

 were noticed on the urinary bladder; 

 in one example, however, none 

 were seen. 



The urinary bladder has no 



lobe merlangus, luscus, virens, pollachius, 



poutassou. 



