344 ON THE ANATOMY OF PLOTUS ANHINGA. [ApT. 4, 



tissue of the corium, which occupies the intermediate space, is very 

 small in amount. Between the tissue and the hair-root is seen a layer 

 of colnmnnr epithelium cells, which in some places are of considerable 

 length. They are continuous towards the surface with the deeper 

 ceils of the stratified epithelium. They represent the 'root-sheaths ' 

 of the cutaneous iiair, and seem to have undergone a horny meta- 

 morphosis. 



" At their extreme ends the roots are entirely different from those 

 of the cutaneous hairs. There is no hair-knob and no papilla ; but 

 the root generally breaks up into two, three, or more short rootlets, 

 each of which tapers to a pointed extremity. This, at least, is the 

 appearance in vertical section ; but transverse sections show that this 

 branching of the hair-root has, at all events in the first instance, 

 more of a laminated character. 



" These rootlets are covered by a layer of cubical epithelium cells, 

 which are continuous with the columnar cells surrounding the hair- 

 root. The latter, as before remarked, is formed merely by the fibrous 

 substance or cortical [)ortion of the hair ; and the fibres wliich com- 

 pose this would therefore seem to be in some way produced by these 

 cells. 



" Some few hairs seem to end by a single tapering rootlet, but most 

 of them spread out and branch in the way described." 



This peculiar hairy mat must act as an excellent sieve to prevent 

 the entrance of solid ]iarticles, fish-bones, fkc. into the narrow in- 

 testines. 



The small intestine is 55 inches long in the female, and 40 inches 

 in the male ; and it is not capacious. The duodenal loop measures 

 5 inches in each limb. The left lobe of the bilobed liver is ahout 

 half the size of the right ; and a gall-bladder of considerable size is 

 present. The large intestine is 6 inches long in the female, and 

 3 inches in the male. There is only a single caecum, exactly like 

 that in the Ardeidae, in my specimens. This conformation of csecum 

 is found in no other Steganopod bird, there being two caeca in all the 

 other geneia. These, in Pelecanus, are a little over an inch in length, 

 in Sulci slightly shorter, whilst in Phalacrocorax, Fregata, and 

 Phaethon they are simple knob-like bodies, nearly globose in form. 

 The rudiment of the vitelline duct is persistent. 



In the distance of its diminutive caecum from the cloaca (in other 

 words, in the length of the large intestine) Plotus differs slightly 

 from its allies. In Pelecanus the large intestine is under 2 inches in 

 length ; and it is much the same in Sula. In Phaethon it does not 

 exceed a quarter of an inch in length. It, however, differs con- 

 siderably in my two specimens, being in both longer than the same 

 in Audubon's specimen. 



In the urino-genital system of Plotus anhinga, in both sexes, the 

 ducts open in the normal manner into the cloaca, just above its 

 lower orifice. Tbis orifice, however, is not on the surface, but is into 

 a cavity, behind the cloaca, which opens externally quite close to the 

 place where the two communicate. Except for this nearly marginal 

 orifice the second cavity is a caecal sac, oval in shape, and about 



