FISH IN GENERAL. 87 



general deprived of salivary glands, they likewise perform 

 their office. Scombri and gadi are abundantly supplied with 

 them, while in labri, siluri, cyprini, and lucii, they are entirely 

 wanting. The vent is placed in very different parts, and 

 does not depend on the position of the ventrals, excepting 

 that in no case is it found before them ; nor is it ever farther 

 back than the commencement of the tail, although the abdo- 

 minal cavity is often prolonged in the form of a sinus consi- 

 derably farther back than the opening of the anus. 



The spleen is likewise found in different locations; it 

 varies in size, but is never found wanting, nor more than one. 

 In general, it lies about the middle of the folds of the intes- 

 tinal canal, receiving arterial blood only, and after elaboration 

 transmitting it to the liver, which also receives the blood of 

 nearly all the intestines. The liver is usually large, and placed 

 somewhat to the left ; in figure, and in the number of lobes, 

 it varies exceedingly, but there is always a gall-bladder; 

 the excretory ducts sometimes, as in tetrodon mola, Lin., 

 opening into the stomach. The hepatic ducts are sometimes 

 numerous. The mesentery is very incomplete, often reduced 

 to a few fraena, in which the vessels and nerves are wrapped 

 up ; this tunic is often prolonged into appendages filled 

 with oily grease, and constituting real epiploons. No con- 

 glomerated glands appear in the mesentery, and nevertheless 

 it is furnished with lacteal vessels, as in other animals ; ab- 

 sorbent vessels are in fact as numerous ; and it may be infer- 

 red, that nature follows in fishes the same system of absorption 

 as in other vertebrated animals. 



Circulation. Fish, like warm-blooded animals, are pro- 

 vided with a complete circulation for the body, another 

 equally complete for the organs of respiration, and with a 

 particular abdominal circulation, terminating at the liver by 

 means of the vena portae ; but the particular character of this 

 part of their organization consists in the branchial circulation 



