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HANDBOOK OF INVERTEBRATE ZOOLOGY. 



6. Two tooth-like prolongations of the anterior edge 

 of the mantle, behind the eyes. 



c. The end of the siphon (Figs. 176, e, 177, d), 



projecting from the mantle 

 chamber; on the median 

 ventral line, bending to- 

 wards the ventral surface, 

 and ending in a transverse 

 oval aperture (Fig. 177, c), 

 which is furnished with a 

 valvular fold. 



d. In the ventral view of 

 the head notice a pair of arms 

 (Fig. 177, a'^), one on each 

 side of the median line. 



Fig, 177. — Male specimen of 

 Loligo Pealii, with the mantle 

 opened to show the body and 

 gills. (Drawn from nature by 

 W. K. Brooks.) 



a. Head. a". Ventral arm. 

 a^. Grasping arm. h. Eye. c. Si- 

 phon, d. Cartilages of siphon, 

 e. Cartilages of mantle. ^. Free 

 edge of mantle, (j. Mantle, h. Gills. 

 i. Rectum, k. Retractor muscles of 

 siphon, m. Ink bag. n. Penis. 

 q. Intestine. r. Branchial veins, 

 s. Gill muscles, t. Branchial ar- 

 tery, u. Branchial heart, o. Renal 

 organs, p. Orifice of renal oi-gan. 

 V. Mantle artery, tc. Posterior venae 

 cavae. x. Visceral sac. y. Mantle 

 cavity. 



Fig. 177. 



e. Outside the bases of these arms a pair of much 

 longer ones, the grasping arms (Fig. 177, a^), each of 



