LIVING BRACIIIOrODA. 357 



elongate, fusiform bodies are more slender and without swellings; the round corpuscles 

 have precisely the same appearance ; the third kind was not present. In L. anatina, 

 (54: 5) the l)lood is a pale crimson lake, or violet, in color. The various corpuscles have 

 often been figured and described, yet it will be of interest to recall their appearance in 

 life. The long, fusiform bodies show the processes of longitudinal divi.sion; the round 

 corpuscles are like those of Glottidia; a few roimd bodies were seen with granulated 

 structure. The filiform body seen in the figure is probably foreign. In the alcoholic D. 

 lamelloi<a (54: G) the blood contained irregularly rounded bodies tinged with brown, 

 these had a slight depression in the centre; larger oblong oval bodies with granulated 

 surface were ova floating in the fluid. The micropyle is shown between the two draw- 

 ings. In T. tfeptentrionalis (54: s) , a variety of irregular, apparently amoeboid particles 

 was found in the blood ; Hancock figures similar bodies as occurring in Hemithyris. 

 From the external glands I squeezed out similar bodies ; certain particles not to be distin- 

 guished from these in form were ciliated and were probably fragments (jf ciliated epithe- 

 lium. Tlie true blood corpuscles are exceedingly minute and I have no- observations on 

 them. 



In T. roreanica, the l)lood was filled with brown granulated cells of minute size, 

 small colorless cells, and colorless granulated cells (54: 7). 



The appearance of the corpuscular elements of the blood of the few forms of 

 Testicardines examined was widely different from that of similar elements in the 

 Ecardines. An examination of the blood of living D. lamel/osa will be necessary before a 

 comparison can be made with the blood corpuscles of the Lhujulidae. 



"Heart of Hancock." 



Having described the lacunal circulation of the blood and the inducing cause of it, 

 and the manner in which it permeates every part of the body, it remains to discuss the 

 so-called heart of Hancock, a vesicular organ which was supposed, by Hancock, to be the 

 true heart, and which is clearly present in most Testicardines and as clearly absent in the 

 Ecardines. This curious little vesicle, which when present is found on the median dorsal 

 surface of the stomach of Terebratulina, Terebi'atalia, Hemithyris, and other genera of the 

 Testicardine group, is certainly an enigmatical organ. It is pyriform in Terebratulina 

 and Hemithyris, and crenulate in Terebratalia. It is an oi'gan very easily detected in 

 those forms possessing it. 



Hancock had discovered in 1852 that the organs which Cuvier, Owen, Vogt, and 

 others had regarded as hearts, opened externally and were in fact oviducts. In a paper 

 read before the British association for the advancement of science in 1856, he announced 



