LOLIGO PEALII LESUEUR 249 



left lower projection of the pallial cartilage and dorsal median 

 projection marking the forward end of the pen; the left lateral 

 fin and the chromatophores. Label also the antero-dorsal and 

 the postero-dorsal surface. The long axis of the squid is the 

 dorso-ventral axis. 



2. Take the squid in your left hand holding the first, second 

 and third pairs of arms between your second and third fingers 

 and pressing down with your thumb the tentacles and the 

 fourth pair of arms; make a drawing showing the front view of 

 the head. Label arms, tentacles, buccal membrane with its 

 seven muscular projections, peristomial membrane, mouth, 

 upper and lower mandible of the beak and, in case the specimen 

 is a female, the horseshoe organ of the buccal membrane. 



3. Make a drawing of the right tentacle showing the peduncle 

 and the club with four rows of suckers. 



4. Cut with a razor a large sucker longitudinally. Examine 

 the surface under dissecting microscope. Make a drawing show- 

 ing the cup with the serrated chitinous ring, the piston and the 

 pedicel. 



5. Make a drawing of the left fourth arm showing the inner 

 marginal membranes and two rows of suckers. In case the arm 

 belongs to a mature male, it will be found to be hectocotylized, 

 i. e., the cups are well developed only in the proximal eighteen 

 pairs of suckers ; from here on they diminish in size and disappear 

 almost completely in the thirtieth to thirty-fifth pair and become 

 gradually normal again toward the end of the arm. 



6. Sever one of the muscular projections of the buccal mem- 

 brane and examine under dissecting microscope. Make a draw- 

 ing of it showing the two rows of suckers. 



7. Make with a sharp scalpel an incision in the mantle along 

 the upper longitudinal median line. Notice that the pen is 

 completely inclosed in a sac. Carefully extract the pen and 

 make a drawing of it. 



8. Turn the squid on its back and holding the mantle firmly 

 with your left hand, make in it with a sharp scalpel a deep 



