64 F. W. FLATTELY. 
groups where it occurs, has been discussed by L. J. Picton (5) and, several 
years previously, by J. T. Cunningham (6). Although the former writer 
is chiefly concerned with the composition of the granules contained in the 
cells forming the body, and of their reaction to various stains, his object 
being principally to examine its claims as an excretory or blood-controlling 
organ, he nevertheless gives a certain amount of attention to its possible 
mechanical function. He quotes the suggestion of Schaeppi (7) in the 
case of Ophelia and of Steen in that of Terebellides Stroemii to the effect 
that the organ has a valvular function. Schaeppi considers this is brought 
about by the swelling of the organ at systole owing to the pressure of 
blood in its meshes. The most telling evidence in favour of a mechanical 
action is that afforded by Cirratulus chrysoderma. Picton says that in this 
species, which is transparent, the heart-body at the point of its greatest 
development almost entirely blocks, at systole, the lumen of the heart, the 
action of which as a blood-propelling organ must be considerably modified. 
It seems certain from what has been noted of the habits of Cirratulus 
that it depends to a great extent amid its somewhat foul surroundings, for 
its supply of oxygen, on the long filaments. There is, therefore, every 
necessity, in view of their delicate nature, for maintaining them turgid. 
Otherwise, they would be extremely liable to breakage and laceration. 
This dithculty would be met by the heart-body acting as a valve and pre- 
venting the blood from being regurgitated. It is certainly remarkable 
that in Arenicola, to which genus the above arguments apply with almost 
equal force, the heart-body is also strongly developed. J. H. Ashworth (8) 
also suggests a valvular function in this latter, and the fact that the organ 
does not appear till after the pelagic larval and post-larval stages are 
complete is not without significance. Some such arrangement would be a 
small compensation for the drawbacks to which Arenicola, with its delicate 
branched gills, must undoubtedly be exposed, through its sandy environ- 
ment. 
External processes with respiratory properties are a common feature in 
Polycheetes, but that does not necessarily imply the same need for a heart- 
body, with the function described, in all. According to Picton a heart-body 
is found in the following groups : Spionidee, Cirratulidee, Terebellidee, Am- 
pharetide, Amphictenide, Chlorhemide, Sternaspide, and Hermellide. 
He omits the Arenicolide, and states that in Magelona the organ is merely 
larval and transitory. As regards the Spionide, I am unable to find any 
confirmation as to its occurrence in this group. Possibly owing to a re- 
vision of the nomenclature the Cirratulide have been included twice in 
this list, under different headings. 
M. Georges Bohn (9) shows how among Annelids adaptation to life in the 
sand is pushed further in some groups than in others, and divides the Poly- 
