1894 THE MICUOSCOPE. 67 



different species. In the Cod, tlie dorsal fin is divided 

 into three distinct parts and the anal fin into trvvo parts. 

 The Bass has an extremely long dorsal fin, extending 

 almost the entire length of the back, and in the Sole the 

 anal fin extends from the anus to the tail, the anas in 

 this case being almost directly under the operculum. 



The position of the anus differs very much ; in some 

 species being far forward, and in others being far back. 

 In some Australian and Queensland fishes, the paired 

 fins instead of being rayed, have a central bone, with 

 others branching from it in much the same manner as 

 the veins of an elm leaf. The fins are also of nearly the 

 shape of this leaf. The scales are small, and when 

 viewed with the low power appear to consist of concen- 

 tric rings * 'cycloid scale" (Fig. 5). 



1. In the dermis beneath the scales are situated the 

 pigment cells which give the skin its colors. These may 

 be easily seen by mounting a small piece of the dermis 

 and viewing with the low power. The cells are stellate, 

 of a dark color, and upon the dorsal side very numerous 

 and well developed, (Fig. 7.) but almost lacking on the 

 ventral side. The cells are arranged in diamond shaped 

 groups (Fig. 6). In the dermis are two sets of parallel 

 fibres which cross each other obliquely. These are 

 known as white fibrous connective tissue. They may be 

 seen quite plainly with the high power glasses. When 

 irrigated with acetic acid (1 per cent) the fibres disap- 

 pear, this being the characteristic reaction of this tissue. 



2. The mouth connects directly with the oesophagus, 

 there being no separate throat. Salivary glands are also 

 lacking. The stomach is quite large, and the intestine 

 leaves it at the upper end, makes a half turn, and then 

 runs straight back to the vent (Fig. 3). There is no 

 large intestine and probably no distinct pancreas. 



The liver lies just in front of the stomach. A short 

 distance in front of stomach, the ductus pneumaticus. 



