350 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 1&16. 



Cephalopoda, head-footed. The mouth is situated in the middle of 

 the tentacular disk and is armed with a pair of formidable parrot- 

 beak-like jaws. Not least conspicuous are the two large, highly 

 specialized eyes situated on the side of the head. Behind the head 

 is a constricted neck. Here we find a cleft, the communicating orifice 

 between the exterior and the mantle cavity ; here also is inserted the 

 tubular siphon which, in reality, is the modified posterior part of 

 the foot and serves as the chief organ of locomotion, for much of the 

 Cephalopod swimming is accomplished by the rapid expulsion of 

 water through this organ by means of the sudden contraction of 

 the muscular mantle. 



The posterior j)ortion of the body may be globular, conic, spindle, 

 or lance shaped, or cylinclric ; it may or may not have lateral flukes, 

 which may serve as organs of locomotion; or may be modified to 

 form a sucker, as in Spirula. The internal organization is also 

 interesting, but we shall content ourselves with the simple statement 

 that the sexes are distinct and that the rather complex brain is 

 shielded in most of them by a cranial cartilage that protects the 

 principal nerve centers, incloses the auditory organs, and supports 

 the very highly developed eyes. An interesting structure found in 

 all the living forms, except the Nautilus, is the ink bag, a glandular 

 sac and a reservoir connected by a duct with the rectum near the 

 anus. This organ produces a dark fluid which the animal is capable 

 of discharging at will. It is usually ejected when the animal is 

 pursued and effectively enwraps it in an impenetrable smudge, thus 

 aiding it to make good its escape. The secretion of the Cephalopod 

 ink bag forms an important element of commerce and our arts, where 

 it is better known under the name of sepia and India ink. 



The living Cephalopods, excepting the Nautilus, are easily divided 

 into two groups or orders. One of these, Decapocla, embraces all 

 the members having 10 feet, while the members of the other order, 

 Octopoda, have but eight (pi. 5). 



Beautifully preserved specimens of squids have been found in 

 those remarkable reliquaries, the Solenhofen lithographic limestone 

 deposits of Bavaria, the hardened ooze of an ancient sea, which has 

 contributed so many chapters to our knowledge of the past. These 

 remains proclaim the presence of the order in the Lower Jurassic. 

 Plate 6 is a photograph of a specimen, U. S. Nat. Mus. Cat. 

 No. 28382, which comes from this formation at Eichstatt and shows 

 the perfect manner in which the soft, enfolding ooze has preserved 

 its record for us. 



FACTS AND FANCIES. 



Size, power, speed, beauty, and intelligence have ever been the 

 elements that have elicited the admiration of man. Add to this the 



