Subcutaneous Vessels in Tail of Lepisosteus C7 



caudal heart in Anguilla. He failed to inject the caudal heart from 

 the caudal vein, but states that when a pulsating caudal heart is seen 

 through a microscope, it is colorless, except a little rose red, due to the 

 adjacent blood capillaries, and that it is in great contrast to the con- 

 necting and surrounding blood vessels. Some year ago I injected some 

 tails of the Mississippi Eiver Anguilla from the dorsal and the ventral 

 subcutaneous trunks, and hope in a later study to be able to demon- 

 strate their connections with the caudal heart. 



In many Teleosts Hyrtl (op. cit., pp. 226-231 and 238, and Figs. 1, 

 2 and 4 a) finds two caudal sinuses situated immediately behind the 

 last vertebra. These sinuses (see Fig. 4) are connected and both com- 

 municate anteriorly with the caudal vein, the orifice being guarded by 

 a valve. The shapes of these sinuses are at variance in different species. 

 According to Hyrtl, the caudal sinus is composed internally of a layer 

 of endothelium, bounded by a layer of longitudinal fibers, outside of 

 which there is an additional layer of transverse fibers. It is described 

 as being contractile and comparable to the lymphatic hearts of the 

 Batrachians. Furthermore, Hyrtl claims that the caudal sinus is no 

 blood reservoir, for its serum is clear, and contains small, round, gran- 

 ular corpuscles. Vogt's description of the caudal sinus of Salmo (op. 

 cit., pp. 135-6, and PI. K, Figs. 3-5, 54) is almost identical to HyrtFs 

 for the perch. He finds a valve in the opening between the two sinuses, 

 and each sinus is said to contain a few muscle fibers, is contractile, and 

 contains a clear fluid in which there are a few granular corpuscle;]. 

 Sappey (op. cit., p. 47, and PL XI, Fig. VI, 6, and PI. XII, Fig. II, 5) 

 speaks of the caudal lymphatic sinuses of Teleosts as being non-con- 

 tractile papillse, which are non-pulsating in the sense of the caudal 

 hearts of the eel and Batrachians, and he was unable to find valves at 

 tlie entrances of these sinuses into the caudal vein. 



As for the Ganoids, Hopkins (op. cit., p. 372, and Fig. 11, s.) repre- 

 sents each caudal sinus in a 53 cm. Amiatus as being a reservoir about 

 1 cm. long by 3 to 5 mm. at its greatest width, situated ventrad of the 

 last vertebrffi. It is said to empty cephalad into the caudal vein, the 

 entrance being guarded by a valve, and to communicate mesad with its 

 fellow sinus. As has already been quoted, the lateral lymphatic trunk, 

 after receiving the caudal trunk and a fork of the dorsal, joins the 

 caudal sinus from the side, near its anterior end. 



The caudal sinuses of Lepisosteus (Figs. 1-6, 16 and 17, L. and K. 

 Cau. S.) have almost exactly the same position as in Amiatus, and 



