LOLIGO PEALII. 123 



full length, turn the flaps aside and see that it lies in a pocket. 

 It probably represents a modified shell that has become entirely 

 inclosed by the mantle. What is its function? 



Pull the pen out of the mantle and draw it. 



With a razor make cross-sections of a squid, a quarter of an 

 inch thick, and arrange them in order, in a little water, as they 

 are made. Identify the parts you have found in dissection. 



Make drawings of the sections that pass through the infra-eso- 

 phageal ganglion, through the eyes, through the liver, and through 

 the heart. 



If time permits, study prepared sections that have pre- 

 viously been made. The structure of the eye and the positions 

 of the parts of the nervous system should receive special atten- 

 tion. 



Specimens of other cephalopods, such as Octopus and Nau- 

 tilus, should be compared with the squid and the adaptations 

 that fit them for their particular lives noted. 



