3G2 A. E. Verrill — North American Cephalopods. 



Gill-opening very wide, extending upward beyond the eyes. Arras 

 long, slender; web rudimentary. Suckers prominent, in two alter- 

 nating rows. Siphon large, iptimately united to the whole length of 

 the lower side of the head ; its free extremity is situated far forward, 

 between the ventral arms. 



The sexes are widely different. The hectocotylized arm of the 

 male is developed in a pedunculated sac. 



There is a large aquiferous pore just behind the base of each ven- 

 tral arm, at the sides of the siphon ; these connect with large, cephalic, 

 aquiferous cavities. The connective cartilages on each side of the 

 base of the siphon consist of a prominent button, with an expanded 

 and recurved anterior edge, which fits into a corresponding deep pit 

 in the mantle-cartilage ; and a deep, triangular pit, in front of the 

 button, which receives the pointed, angular, cartilaginous tubercle 

 of the mantle-cartilage. The posterior border of the base of the 

 siphon forms a broad collar, within the mantle border. The lateral 

 openings to the gill-cavity, on the sides of the neck, extend up as far 

 as the upper side of the eyes; opposite and below the eyes, they are 

 large, but internally are interrupted by two muscular bands on each 

 side, one running back from the head to the mantle and one going 

 back from the base of the siphon, opposite the connective cartilage. 



The median septum of the gill-cavity is strong, but short, com- 

 mencing a little behind the base of the siphon and extending only a 

 short distance back, but expanding in length as it joins the ventral 

 surface of the mantle; behind it the two halves of the gill-cavity are 

 connected by a wide opening. The peritoneal membrane is strong, 

 and specked with dark chromatophores. 



Parasira catenulata steenstrup. 



Octopus tuherculatus Risso*(?), Hist. nat. de I'Eur. merid., iv, p. 3, 1826 (t. d'Orb.) 

 Octopus catenuMus Ferussac, Poulpes, pi. 6, bis, ter., 1828 (t. D'Orbig.) 

 Philonexis tuherculatus Fer. and D'Orb., Cepli. Acet., p. 81, pi. 6, bis, ter. 

 Parasira catenulata Steenstrup. 



Verrill, Aroer. Journ. Sci., xix, p. 293, Apr., 1880. 



Plate XXXIII, figures 2, 2a. 

 Female: Body relatively large, swollen, rather higher than broad, 

 dilated below, larger in front, obtusely rounded posteriorly ; upper 

 surface smooth or finely wrinkled; loAver surface covered with promi- 

 nent rounded verruc:e or small hard tubercles, which are connected 

 too-ether by raised ridges, five (sometimes six) of which usually run 

 to each tubercle, thus circumscribing angular depressed areas, each 



