CEmALOPODA. 167 



The shell of tlie living decapods is either a horny "pen" 

 [gladius) or a calcareous " bone" {sepion) ; not attached to tho 

 animal by muscles, but so loose as to fall out when the cyst 

 which contains it is opened. In the genus spirula it is a delicate 

 spiral tube divided into air-chambers by partitions {septa). In 

 the fossil genus spiruUrostra a similar shell forms the apex of 

 a cuttle-bone ; in the fossil conoteuthis a chambered shell is 

 combined with a pen ; and the belemnite unites all these 

 modifications. 



The decapods chiefly frequent the open sea, appearing periodi- 

 cally like fishes, in great shoals, on the coasts and banks. (Owen, 

 D'Orbigny.) 



Family III. — TErTHiD^. Calamaeies, or Squids. 



Body elongated ; fins short, broad, and mostly terminal. 



Shell (gladius or pen) horny, consisting of three parts, — a shaft, 

 and two lateral expansions or wings. 



Sub-family A. Mijopsidce, D'Orbigny. Eyes covered by the 

 skin. 



LoLiGO. {Pliny) Lamarck. Calamary. 



Synonym, teuthis (Aristotle), Gray. 



Type, L. vulgaris (sepia loligo, L.). Fig. 1. PI. I., fig. 6 

 (pen). 



Pen lanceolate, with the shaft produced in front ; it is multi- 

 plied by age, several being found packed closely, one behind 

 another, in old specimens. (Owen.) 



Body tapering behind, much elongated in the males. Fins 

 terminal, united, rhombic. Mantle supported by a cervical 

 ridge, and by two grooves in the base of the funnel. Suckers in 

 two rows, with horny, dentated hoops. Tentacular club with 

 four rows of suckers. Length (excluding tentacles) from 3 

 inches to 2| feet. Fourth left arm in male metamorphosed at 

 its extremity. Steenstrup* says two species are confounded 

 under the name of L. vidgaris. The variety occurring in the 

 Atlantic, and not in the Mediterranean, is a distinct species {L. 

 Forhesii, Stp.). In it the fourth left arm has twenty-three pairs 

 of suckers well developed, five less developed, while the arm 

 beyond the twenty-eighth pair is occupied by forty pairs of 

 conical elongated papillae, which correspond to forty pairs of 

 suckers. Steenstrup recognises only seven living species of 

 Loligo, all the others so called being only varieties of these. 



* Annals of Natural Historj-, 1S57. 



