ROBSON— ON THE CEPHALOPODA 



433 



Family 8. Ommatostrephidae. Stenoteuthis. 



S. bartramii (Le Sueur). (Plate 66, fig. 1.) Journ. Acad. Nat. Sci. Philadelphia, 

 ii. pt. I. 1821. 90 t. 7. (For a full synonymy cf. Pfeffer (16).) 



Two examples, $ (young), " flew on board " 30 miles W. of the Centurion Bank 

 (Chagos Is.), (i4'16). 



A complete account of the anatomy -of this cosmopolitan form is very desirable on 

 account of its peculiar "flying" habit. Unfortunately the amount of material to hand 

 prohibits the preparation of such an account in the present instance; nor, in fact, does 

 the condition of the animal here described from dissection, favour a satisfactory account, 

 particularly with regard to the genitalia. 



The branchice are slender and elongate resembling a quill pen in general appearance. 

 They are relatively very long, in individuals of 80 mm. length measuring 33 — 34 mm. 

 There are 56 (±1) laminae, the distal ones being very minute. The scheme of plication, 

 which is tolerably simple, is shewn in fig. 1 c. 



The anus exhibits two lateral valves, elongate and auriform in appearance. 



Internal anatomy. 



The heart (fig. 1 b) is fairly regular in shape and is elongate in its sagittal axis. 

 The anterior and posterior aortse originate at the anterior and posterior extremities. In 

 the two specimens there were no traces of auiicles. It is possible that the swellings at 

 the base of the efferent vessels represent these. 



The branchial hearts are large, irregularly-shaped organs, each exhibiting an 

 appendix and partly separated from it by a very deep groove in which the afferent vessel 

 terminates. 



Posteriorly the posterior vena cava appears to arise from two very long and narrow 

 blood sinuses. From one of these a main vessel was found debouching into the vena cava. 

 On the other side the specimen was too badly preserved to allow dissection to trace a 

 similar connection; though there is no reason to suppose an asymmetrical condition. 



Such blood sinuses are apparently rare in the Cephalopoda and may be in some way 

 related to the animal's habit of "flying" or leaping from the water. 



The renal papillae are found about 2 mm. from the base of the branchiae between 

 the latter and the intestine. 



The stomach appears to bear two appendices (fig. 1 a), one of these a rounded sac 

 lying anteriorly, the other a narrow elongate structure occupying a terminal position. 



The first appears to be plicate internally and may represent the true stomach described 

 for Loligo pealeii by Verrill (18), while the second may be the equivalent of his "caecal 

 lobe " described for the same animal. 



The testis is a thin elongate organ closely applied to the left-hand blood sinus and ter- 

 minating anteriorly in a piriform mass of coiled tubes, the external aperture being dorsal 

 to the gill heart and just near its posterior extremity. From this aperture project the 

 ends of two tubules, apparently the terminal portion of Needham's sac and the prostate (?). 

 It is very much to be regretted that the condition of the single animal available for dissection 

 precluded a complete examination of the genitalia. 



i^ LIBRARY' 33| 



