22 Fishery Board for Scotlaiid. 



tumours do not show the brown central region. In some cases the 

 brown region sends an angle to near the surface : in others it is 

 median. 



Ling. — A tumour found inside a ling was about H inch (4 cm.) in 

 diameter. It had a thick wall, and contained an amber-coloured 

 fluid. The wall on one side was thickened, and contained what 

 appeared to be a quantity of coagulated blood. 



Tumour on Skin of Porbeagle Shark (Lamna comubica). 



The fish was a male about 4 feet (120 cm.) in length. A large 

 wart-like, but soft, excrescence projected from the side (T., fig. 

 112). It was situated on the lateral line, and at about the middle 

 of the length of the fish. The skin shows deep longitudinal grooves 

 (<jr.). The tumour is a flattened hemisphere about 1^ inch (4 cm.) 

 in diameter (fig. 99), rising at its highest about § inch (15 cm.) 

 from the surface of the side. It is not pigmented black as the skin 

 of the fish is. The black pigment (p.) only extends to the edge of 

 the tumour: the rest is without pigment. 



The tumour is fibrous, and appears to be an excessive development 

 of the derma. It has probably been formed in consequence of an 

 injury to the skin. A portion of the pigmented skin had been 

 destro}"ed, and the white tough, many-layered derma (d.) had been 

 exposed. The derma layers have grown out into a highly-vascular 

 fibrid pad. The upper layers run into the tumour: the bottom 

 layers are separated and thickened a little. The blood supply was 

 visible between the separated layers. 



Drew describes a similar skin tumour on Gadus merlangus, and a 

 fibro-sarcoma on a Raia macrorhynchus. 



Tumour on a Plaice (Pleuronedes platessa). — The tumour, which 

 was attached to the lower side of the fish by a sort of neck, was 

 flattened (fig 93). It rose about f- inch (9 mm.) above the surface of 

 the skin. A section through the fish and the tumour is shown in 

 fig. 96. The tumour consisted of fibrous tissue. A cavity (ca.) extends 

 a little way into the side of the fish. It had penetrated through the 

 muscle (m.) as far as the yellow fatty tissue (ft.). Part of the muscle 

 (in.) had been replaced by fibrous tissue. The muscles are shown 

 striated. The tumour would appear to be a development of the 

 aponeurosis. 



Johnstone describes two similar tumours on the plaice (1909). 

 Drew records a fibro-sarcoma on the same species. 



Tumour on a Lemon Sole (Pleuronedes microcephalous ). — The 

 fish measured 14| inches (36 cm.) in length, and was in good con- 

 dition. The tumour was on the lower side (fig. 102). It was soft, 

 and greenish in colour. It measured 25 by 21 cm. The skin 

 covering the tumour contained scales, except over the central region. 

 The scale-pits were further apart than on the normal regions. 



A section of the tumour is shown in fig. 100. It consists of 

 fibrous, spongy material, in which are several large cavities. From 

 tlie latter much dark red fluid was pressed. The fluid appeared to 

 be blood possibly disorganised. The fluid, when protected by a 

 cover glass, had not coagulated after an interval of three hours, 

 except at the edges. Some of the fluid exposed to the air had dried 

 up. Fig. 95 represents some of the yellow corpuscles accompanied 



