836 THE CRUSTACEA. $ 288. 
2. With the other Crustacea, excepting the Myriapoda, 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. 
During 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 aspect. This heart has arteries 
passing off in front, behind, and below, and the returning venous blood. 
enters it through venous orifices on its upper lateral portion.? With the 
Poecilopoda, 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; but with the 
2 There are, usually, in the polygonal heart of 
the Decapoda, three anterior arterial orifices, two 
below and one behind. These open distinctly into 
asmany main arteries ; see Swammerdamm, loc. 
cit. p. 87, Taf. XI. fig. 8 (Pagurus); Roesel, loc. 
cit. p. 58, Taf. IX. fig. 14, and Suckow, loc. cit. 
p. 58, Taf. IX. fig. 1, Taf. XI. fig. 2-4 (Astacus) ; 
Audouin and Milne ELdwards, Ann. d. Sc. Nat. 
XL. 1827, p. 353, 363, Pl. XXIV. XXVIII. fig. 1; 
and Milne Edwards, Hist. d. Crust. Pl. V. VII. 
(Maia and Homarus), and Cyclop. of Anat. loc. 
cit. p. 775, fig. 418 (Cancer). Not so easily seen 
are the six venous orifices which always are only 
valvular fissures, chiefly because they do not open 
into veins. According to Lund, and 4. W. F. 
Schultz (Isis, 1825. p. 594, Taf. III. fig. 2-4; 
Ibid. 1829, p. 1299, (Homarus), and 1830, p. 1226, 
with the figure of p. 1228, (Maiq)), 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. XTL. 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 dudouin and Milne Edwards (Ann. 
d. Sc. Nat. loc. cit. p. 357, 364, Pl. XXVI. fig. 3, 
N."") have not observed in the heart of Homarus 
and Maia only the two lateral orifices. This 
last naturalist (KHist. d. Crust. I. p.94. Pl. V. VL.) 
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 5 but, judging from the 
beautiful figures of them given by Owen (Catal, of 
the Physiol. Ser. II. Pl. XV. h. h, Pl. 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. ff.” See also the description 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. 
gén. sur l’ anat. comp. des anim. articulés, p. 346, 
and especially Van der Hoeven, loc. cit. p. 18, 
Pl. Il. 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 belonging to the venous system. With the 
Isopoda, the tubular heart is continuous with 
an anterior and a posterior aorta ; it receives only 
three to five pairs of lateral vessels which have been 
regarded sometimes as arterial and sometimes as- 
venous ; see 7'reviranus, Verm. Schrift. I. p. 58. 
65, Taf. VIII. fig. 46, and Taf. IX. fig. 55 (Por- 
cellio and Armadillidium) ; Brandt, Med. Zool. 
IL. p. 75, Taf. XV. fig. 38 (Porcellio) ; Lereboul- 
det, loc. cit. p. 131, Pl. V. fig. 33 (Lygidium) ; 
Rathké, in the Neuest. Danzig. Schrift. I.p.122 (ido- 
thea), and Nov. Act. Nat. Cur. XX. p. 81 (Adega). 
It is, however, very prolable that these orifices are 
arterial, for they open into vessels, and, moreover, 
the venous orifices are found, as with Limulus, on 
the dorsal surface of the organ. For the Am- 
phipoda, Gammarus pulex may he cited as a 
type, and of which the heart as a cylindrical ves- 
sel occupies the axis of the anterior segments of the 
body. In this animal may be very easily seen 
how the blood, with the diastole, enters the heart 
through the several dorsal venous orilices, 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 
have only the imperfect details given by T'revi- 
ranus (Verm. Schrift. II. p. 8), and Roussel de 
Vauzeme (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 
posterior Ostium venosum, and passes out into 
the body through an anterior Ostium arteriosumn. 
If this organization is confirmed, Mysis will differ 
remarkably in this respect from the Isopoda, Am-~- 
phipoda, &c., but especially from another Stoma~ 
pode genus, — Squidda ; for in this last, the heart 
with its anterior, posterior and lateral orifices, 
reaches its greatest development, occupying the 
entire abdominal cavity except the cephalothorax, 
and sends off laterally fourteen to seventeen pairs. 
of arteries, beside being perforated on its upper 
portion by various pairs of venous orifices ; see 
Duvernoy, Ann. d. Sc Nat. VILL. 1837 p, 42, Pl. 
