A MANUAL OF ZOOLOGY 29 



below the intestine. Compare the auricles and the ven- 

 tricle as to structure. 



THE NERVOUS SYSTEM— Preserved specimens are 

 to be used here. Separate the palpi and find the cerebral 

 ganglia just under the skin. Nerves may be traced to the 

 adductor muscle and to the pedal ganglia in the foot. 

 Separate the gills at the posterior end of the body and 

 find the visceral ganglia. 



THE EXCRETORY SYSTEM— Find the kidney as a 

 dark colored tube with spongy walls under the pericard- 

 ium. The renal aperture will be seen as a small pore at 

 the anterior end of the pericardium. Find the genital 

 aperture near the renal aperture. Study live specimens 

 in an aquarium containing three or four inches of sand. 

 There will thus be several interesting observations made 

 on the habits of the animal. Specimens will be preserved 

 in chromic acid and cross sections made for gross struc- 

 ture. 



II. CEPHALOPODA 

 Lollgo Pealii (Squid.) 



The habitat of the squid usually corresponds with that 

 of the larger number of salt water fishes. This is because 

 he can thereby obtain his food to a better advantage. 

 Fishermen often get large quantities of squid in their 

 nets, and from them squid may be obtained during certain 

 seasons of the year at a small cash outlay or by a little 

 trouble. 



For dissection squid should be preserved in formalin 

 or alcohol, preferably the former. The can containing 

 them should contain formalin 4 per cent, also som'e iron 

 filings or old nails. Specimens thus preserved show good 

 hardening and also the "denser parts are colored a little 

 darkerHhan the others, "thereby giving a. better definition. 



EXTERNAL FORM^wfiat is the general form of the 

 body? What is the shape of the animal as to anterior and 

 posterior ends? Is the head movable? Notice the mouth 

 in the space between the arms. How meny arms are 

 there? In some specimens a peculiar formation is seen 

 projecting from the mouth. What is this? 



Notice the eyes. ' Note their size. Copipare them with 

 those of the lobster- or locust. 



