336 



THE CRUSTACEA. 



'§>283. 



2. With the other Crustacea, excepting the Mjriapoda, the heart has, 

 likewise, the form of a short simple sac, or that of a simple tube. In 

 both cases, it is perforated by very numerous arterial and venous orifices. 

 Durinflf the systole, the blood is propelled through the arterial orifices lead- 

 ing, nearly always, into vessels of the same nature ; at the same time, the 

 venous orifices are closed by valves, which open, however, during the diastole, 

 to allow the ingress of the blood into the heart. With the Decapoda, the 

 heart is vesiculiform, situated in the middle of the cephalothorax, and its 

 projecting corners often give it a star-like as))ect. This heart has arteries 

 passing otf in front, behind, and below, and the returning venous blood 

 enters it through venous orifices on its upper lateral portion.'-* With the 

 Poecilopodn, Isopoda, Amphipoda, and probably, also, with the Laemodi- 

 poda, and Cirripedia, the tubular heart, occupying a large portion of the 

 anterior and middle regions of the back, sends off arteries before, behind, 

 and laterally, and receives the venous blood through lateral venous ori- 

 fices.^"* This organ is most highly developed with the Stomapoda, where 

 it occupies nearly the whole length of the body like a tube j'^* but with the 



2 There are, usually, in the polygonal heart of 

 the Decapoda, tln-ee anterior arterial orifices, tiro 

 below and one behind. These open distinctly into 

 as many main arteries ; see Swammerdamm,l<K. 

 cit. p. 87, Taf. XI. fig. 8 (Pagurus) ; Rnesel, loc. 

 cit. p. 58, Taf. IX. fig. 14, and Suckow, loc. cit. 

 p. 58, Taf. IX. fig. 1, Taf. XI. fig. 2-i (Astacus) ; 

 Audouin and Milne Edwards, Ann. d. So. Nat. 

 XI. 1827, p. ;S53, 363, PI. XXIV. XXVIII. fig. 1 ; 

 and 3Iilne Edwards, Hist. d. Crust. PI. V. VII. 

 {Maia and Homarus), and Cyclop, of Anat. loc. 

 cit. p. 775, fig. 418 (Cancer). Not so easily seen 

 are the si.x venous orifices which always are only 

 valvular fissures, chiefly because they do not open 

 into veins. According to Lund, and A. W. F. 

 Schultz (Isis, 1825. p. 594, Taf. III. fig. 2-4; 

 Ibid. 1829, p. 1299, {Hoynarus), anil 1830, p. 1226, 

 with the figure of p. 1228, (Maia)), the heart of the 

 macrourous Decapoda has two upper, two lower, and 

 two lateral venous orifices, while that of the Brachy- 

 ura have only four upper and two lateral. Krohn 

 (Isis, 1834, p. 524, Taf. XT I. fig. 1-3), has con- 

 firmed this observation with the crawfish. Suckow, 

 however (loc. cit. p. 58, Taf. XI. fig. 2, a. a.), did 

 not perceive in this species only the two upper ori- 

 fices, while Audnuin and Milne Edwards (Ann. 

 d. Sc. Nat. loc. cit. p. 357, 364, PI. XXVI. fig. 3, 

 N."|-) have not oljserved in the heart of Homarus 

 and Maia only the two lateral orifices. This 

 last naturalist (Hist. d. Crust. I. p. 94. PI. V. VI.) 

 refuses to admit the description of the heart of 

 the Decapoda given by Lund, and brings to 

 his support (Cyclop, loc. cit. p. 777) Hunter''s 

 preparations of the lobster ; but, judging from the 

 beautiful figures of them given by Owen (Catal. of 

 the Physiol. Ser. II. PI. XV. h. h. PI. XVI. fig. 2, d. 

 d. and especially fig. 1, f f. f.) these are just the pre- 

 parations to support the view of Lund, Schultz, 

 and Krohn. I, at least, have perceived distinctly 

 the upper, lower and lateral venous orifices, as 

 "the three orifices of the veins passing. into the 

 heart, f. f. f." See also the descrijition of Owen 

 of the heart of the lobster in his Lectur. on Comp. 

 Anat. p. 179, fig. 91. 



3 For the heart of Limulus, see Straus, Consid. 

 gen. sur 1' anat. comp. des anim. articults, p. 346, 

 and especially Fan der Hoeven, loc. cit. p. 18, 

 PI. II. fig. 9. Beside the anterior and poster- 

 ior arterial orifice, there are, with these Crus- 

 tacea, seven others belonging to the seven pairs 

 of lateral arteries, and on the dorsal portion 

 of the organ, an equal number of valvular open- 

 ings belonghig to the venoua system. With the 



Isopoda, the tubular heart is continuous with 

 an anterior and a posterior aorta ; it receives only 

 three to live pairs of lateral vessels which have been 

 regarded sometimes as arterial and sometimes as 

 venous ; see Treviranus, Verm. Schrift. I. p. 58. 

 65, Taf. VIII. fig. 46, and Taf. IX. fig. 55 {Por- 

 cellio and Armadillidium) ; Brandt. Med. Zool. 

 II. p. 75, Taf. XV. fig. 38 (PorcelUo) ; Lereboul- 

 let, loc. cit. p. 131, PI. V. fig. 33 {Ly s: idium) ; 

 Ralhki, in the Neuest. Danzig. Schrift. I. p. 122 (/do- 

 thea), and Nov. Act. Nat. Cur. XX. p. 31 {Aega). 

 It is, however, very proliable that these orifices are 

 arterial, for they open into vessels, and, moreover, 

 the venous orilices are found, as with Limulus, on 

 the dorsal surface of the organ. For the Am- 

 phipoda, Gammarus pulex may be cited as a 

 type, and of which the heart as a cylindrical ves- 

 sel occupies the a.-ds of the anterior segments of the 

 body. In this animal may be very easily seen 

 how the blood, with the diastole, ent«;rs the heart 

 through the several dorsal venous orifices, and 

 how, with the systole, it is thrown forwards, back- 

 wards and laterally through the arterial openings. 



We have not yet complete researches on the 

 heart of the Cirripedia ; but since Martin St. Ange 

 (loc. cit. p. 18) states that these animals have a 

 dorsal vessel with lateral trunks, it may be con- 

 cluded that their heart is like that of the Amphi- 

 poda, Isopoda, &c. As to the Laemodipoda, we 

 liave only the imperfect details given by Trevi- 

 ranus (Verm. Schrift. II. p. 8), and Roussel de 

 Vauzime (loc. cit. p. 254), according to which 

 there is, with Cyamus, only a simple tube opening 

 before and behind ; and we are therefore unable to 

 say whether this heart is formed after the first or 

 second type indicated in the text. 



4 With Mysis, the heart consists, according to 

 Frey (loc. cit. p. 21), of a dorsal vessel extending 

 from the cephalothorax into the back part of the 

 body ; but the blood enters it only through a 

 jjosterior Ostium venosum, and passes out into 

 the body through an anterior Ostium arteriosum. 

 If this organization is confirmed, Mysis will differ 

 remarkably in this respect from the Isopoda, Am- 

 phipoda, &c., but esi)ecially from another Sloma- 

 pode genus, — Squilla; for in this last, the heart 

 with its anterior, i)osterior and lateral orifices, 

 reaches its greatest development, occupying the 

 entire abdominal cavity except the cephalothorax, 

 and sends otf laterally fourteen to seventeen pairs 

 of arteries, beside benig i)orforated on its upper 

 j)ortion by various pairs of venous orifices ; see 

 Duvernoy, Ann. d. Sc. Nat. VIII. 1837, p. 42, PI. 



