342 
ary appendages, which hang 
THE CRUSTACEA. 
$ 286. 
freely from the base of some of the feet, or 
are inserted isolatedly on the sides of the body.“ 
4, The Phyllopoda have, at the base of each of their numerous swim- 
ming feet, an ovoid or lanceolate branchial lamella, pointing forwards, 
It is quickly distinguished by its thin, glabrous covering, in opposition to 
that of the other divisions of feet, which are bristled. 
5. With the Amphipoda, the rapacious and ambulatory feet, excepting the 
first and last pairs, are those only which are provided with respiratory organs. 
These last consist of oval or round glabrous lamellae, situated internally at. 
the base of the five middle feet. 
They receive, constantly, fresh water by 
the movements of the three anterior pairs of post-abdominal feet, which 
act as gyratory organs. © 
4 With Phyllosoma, there is, at the base of the 
anterior feet, a small, ovoid, pedunculated append- 
age, which may perhaps be regarded as a rudi- 
mentary branchia ; see Milne Edwards, Hist. 
Nat. d. Crust. IL. p. 474, Pl. XXVIII. fig. 15, a. 
It is remarkable that, with another Stomapode 
genus, Squilla, there are at the base of the ten 
rapacious feet similar pedunculated appendages of 
the form of oval lamellae (Milne Edwards, Hist. 
Nat. d. Crust. IL. p. 512, Pl. XXVI. fig. 15, Pl. 
XXVII. fig. 13, 14, b.). These, also, would be re- 
garded as rudimentary branchiae, did not these 
Crustacea have distinct branchial organs (sce 
below). With Alima, the oval feet have some- 
times very rudimentary branchiae in the form of 
simple vesicles or ramified processes (Milne Ed- 
wards, loc. cit. II. p. 506). With Caprelia, and 
Aegina, the first two posterior abdominal seg- 
ments have, upon the sides, 4 simple, very soft, 
pyriform branchia; while with Leptomera, there 
is a vesicle of the same nature at the base of the 
six feet of the first three posterior abdominal seg= 
ments ; see Milder, Zool. Danic. Tab. LVI. fig. 5, 
and Tab. CI. fig. 2; Templeton, Transact. of the 
Entomol. Soc. I. p. 193, Pl. XXI. fig. 7, f. 5 and 
Kréyer, Naturhist. Tidskr. IV. p. 490, Pl. VI- 
VIII. With Cyamus, the respiratory organs are 
even more developed. They consist of four long, 
simple cylinders inserted on the sides of the first 
two posterior abdominal segments, and projecting 
over the back ; see T'reviranus, Verm. Schrift. IL. 
p. 9, Taf. I. fig. 1-3, and Beobacht. aus. d. Zoot. u. 
Physiol. p. 32, Taf. VIL. fig. 48—50 ; also Kréyer, 
loc, cit. IV. p. 474, Pl. V. fig. 70-76 ; and Roussel 
de Vauzéme, loc. cit. p. 248, Pl. VIII. ; according * 
to this last mentioned author, Cyamus ovalis has 
four double, branchial cylinders. These branchiae 
of Cyamus have often been taken for metamor- 
phosed feet, but it is only necessary to examine 
them in their earliest condition :in order to be con- 
vinced that they are special organs (Milne Ed- 
wards, Ann. d, Sc. Nat. III. 1835, p. 329, Pl, XIV. 
fig. 14). At this epoch they are as pyriform as those 
inserted on the side of the feet of Leptomera. The 
passage to Squil/a, whose branchiae are more highly 
developed, is made by Cynthia. Each anal foot has 
here a bifurcated branchia, the two cylindrical 
divisions of which are curved towards each other 5 
see Milne Edwards, Hist. Nat. d. Crust. IL. p. 
462, Pl. X. fig. 5. 
5 The delicate branchial lamellae usually assume 
after death the form of vesicles, from being filled 
with blood, a phenomenon already mentioned (§ 285, 
note 2). But, formerly, they were taken for special 
organs whose function was unknown, and Berthold 
(sis, 1830, p. 693) has regarded those of Apus as 
-Mnale genital organs; while the remaining pilose 
divisions of swimming feet were, according to him, 
respiratory organs. : 
These branchiae are easily perceived with dpus 
after death, and from the form which they then 
assume, they have long been known as the prob- 
lematical red sacs (Schaeffer, loc. cit, Tab. IL. ILL. 
VI.; Zaddach, loc. cit. p. 14, Tab. II. fig. 13, B. 
Tab. XIV.). In 1880 (Isis, p. 429) I gave the cor- 
rect interpretation of these organs which, like the 
swimming feet of these animals, diminish in size 
from before backwards ; but, already, before me, 
Loschge (Naturforsch. Stick. XIX. p. 68, Taf. IT. 
fig. 6,7, 10) had recognized their nature. With 
Limnadia, and Isaura, the branchiae are very 
long and of a brown-red color, but are wanting on 
the last swimming feet ; see Brongniart, loc. cit. 
p. 86, Pl. XIII. fig. 7,8; Straus, Mus. Senckenb. 
loc. cit. p. 124, Taf. VII. fig. 13, 14, r., 15, kk. 5 
Joly, loc. cit. p. 299, Pl. VIL. fig. 2, 6,7, f and 
Pi. VILL. fig. 8, f. .With Chirocephalus, Bran- 
chipus, and Artemia, they have a more oval form 
and exist on all the swimming feet. Rathké (Zur 
Fauna der Krym. p. 108, Taf. VI. fig. 14, 19-21), 
has figured, probably from dead individuals, those 
of Artemia as vesicular bodies, In the figures of 
Jurine (Hist. d. Monocl. Pl. XXI. XXII.), made 
for the memoir of Prévost, the branchiae of Chiro- 
cephalus are not seen at first, but with a little at- 
tention may be discovered. Gaede (Wiedemann's 
zool. Magaz. I. p. 88), Berthold (Isis, 1830, p. 689, 
Taf. VII. fig. 1), and Zaddach (loc. cit. p. 11, Tab. 
I. fig. 17, Tab. II. fig. 10) have regarded the large 
dorsal shield of Apus as a respiratory organ, 
since its lateral halves are traversed by blood-cur- 
rents running close to each other (Schaeffer, loc. 
cit. p. 72, Tab. I. fig. 5, b. b.), and thence passing 
directly towards the anterior extremity of the 
heart. 
Indeed, from the vascularity and delicateness of 
the under surface of this shield, one would be quite 
disposed to attribute to these parts a participation 
in the respiratory act. 
6 For a long time, the multi-articulated, bristly, 
anal feet of these small Crustacea were regarded us 
branchiae, for the true branchiae are quite concealed _ 
under the internal surface of the anterior fect. 
Even after the attention had been directed to these 
organs, their form was often misapprehended:; for 
when these animals are a long time dying, their 
branchiae are changed, from congestion, into ampul- 
lae. With the Amphipoda, it is easy to distinguish 
the branchial lamellae from the incubatory lamellae 
at their side, for the borders of these last are bris— 
tled ; see Straus, loc. cit. p. 57, Pl. LV. fig. 10, 11, 
h. (Hiedla) ; Zenker, loc. cit. p. 8 (Gammarus) ; 
Milne Edwards, Ann. d. Sc. Nat, XX. 1880, p. 
357, Pl. X. fig. 7, Pl. XI. fig. 1, also Ibid. IIT. 1835, 
Pl. XIV. fig. 9, and Hist. d. Crust. IIL. p. 6, Pi. 
IL. fig. 15, ¢., Pl. XXX. fig. 1, 13, 16 (Gammarus 
Phronima, Vibilia, Hyperia). According to 
Savigny’s figure (Descrip. de Hgypte, loc. cit. Pl. 
