526 



THE VOYAGE OF H.M.S. CHALLENGER. 



investigation employed, a historical review is drawn up of the results obtained or errors 

 committed by previous writers on this branch of research, and after a careful record of Dr. 



Delage's own observations, a graphic representation is submitted of the affinities between 

 different groups of Crustacea to which those observations seem to point : — 



Podophthal-mes Isopodes Amphipodes Laemodipodes 



Cumaces Anthunidds 



Apseudes 



anaid^s 



Dr. Delage confirms the view of Fritz Miiller that the number of lateral slits in the Amphipodan 

 heart consists, with rare exceptions, of three pairs [without, however, noticing that la 

 Valette had already in 1857 plainly stated this fact in regard to Gammarus pufea7ms, and that 

 Spence Bate, Sessile-eyed Crustacea, vol. i. p. xxxii., 1868, describes the course of the blood 

 in the Amphipoda returning to the heart, "which it enters by three lateral pulsating oblique 

 apertures"];, he gives G. 0. Sars the credit of having first clearly indicated the existence 

 of a posterior aorta with definite walls ; he finds that Wrzesniowski has recognised the 

 existence of the hinder cardio-aortic valve ; has described exactly the lower aorta with its 

 termination in the hinder part of the ventral sinus by three openings, two lateral and one 

 terminal ; has described the course and branches of the upper aorta, but without seeing the 

 valve that separates it from the heart, or the pericerebral vascular ring ; has been the first 

 to recognise that the blood which circulates in the appendages is contained in true vessels, 

 and, lastly, has had a glimpse of the pericardium, since he speaks of a venous cavity above 

 the heart. [In the Zoologischer Anzeiger for 1879 Wrzesniowski very minutely describes 

 the valve apparatus at both extremities of the heart.] Delage believes himself to have 

 proved by injections that, in the principal joints of the legs, instead of occupying half the 

 total breadth, leaving the other half to the venous current, the arterial vessels wind, 

 perfectly rounded and defined, between the muscles, only communicating here and there 

 with the corresponding venous vessels, which are also on their part perfectly individualised. 

 He therefore rejects the view that the cavity of each limb is simply subdivided into two 

 compartments by a single longitudinal membrane. His further discoveries concern the 

 existence of the anterior cardio-pericardiac valve [abeady known to Wrzesniowski], a peri- 

 cardium with perfectly definite and continuous walls, a peri-oesophageal vascular collar 

 formed by two branches of the anterior aorta, and a vascular ring formed by the aorta 

 round the brain, a ring characteristic alike of the Amphipoda and the Ltemodipoda. His 

 observations were made principally on Talitrus locusta, Latr., Gmnmai-us locusta, Fabr., 

 in both of which the lateral orifices of the heart are found in the second, third and fourth 

 segments of the perfeon ; on Montagua monocuJoides, Sp. Bate, in which he could not 

 discover an orifice in the second segment; and on CoroxjMiim lontjicorne, Latr., in which 

 there is but one pair of lateral orifices, situated in the fourth segment. The Corophinae 

 are separated from the (other) Amphipoda, not only by this distinction, but also by the 

 absence of two vessels proceeding from the upper extremity of the heiirt and designated 

 " facial arteries," as well as by the absence of a vascular ring round the so-called " renal 

 organ," and by the circumstances that the lower aorta is not terminally divided, and that 

 the pericardium, instead of occupying the whole length of the body, is limited to the perseon. 



