854 



THE CRUSTACEA. 



^292. 



the large oviducts of which open at the base of the first pair of feet, near 

 the ineSian line of the body/''' 



With the Laeraodipoda, Isopoda, Amphipoda, and Mysina, there are 

 two simple ovarian tubes wound about the digestive canal ; these oviducts 

 are sometimes terminal, sometimes lateral. The two vulvae are usually 

 situated on the internal side of the fifth pair of feet.'^' The eggs, after 

 laying, are always deposited in an incubating pouch, situated beneath the 

 anterior extremity of the body, and the walls of which are formed in part 

 by from two to five pairs of imbricated, and often concavo-convex lamel- 

 lae. ^^' These last are generally bristled on their borders, and are chiefly 

 developed at the epoch of procreation, after which they disappear.'^"' 



The ovaries of the Squillina differ remarkably from those of the other 

 higher Crustacea. They consist of numerous, ramified lobes, filling the lat- 

 eral portions of the posterior abdominal segments, and the digitations of 

 which extend even into the last and flattened caudal segment. All these 

 divisions of each ovary join in a large, long tube, which surrounds the 

 digestive canal. The portion of the ovary contained in the three segments 

 to which are attached the ambulatory feet, sends towards the ventral sur- 

 face, three branches, which join, upon the median line beneath the abdomi- 

 nal cord, with those of the opposite side, and form, in the middle of each of 

 these three segments, a round sinus. These sinuses are connected by longi- 

 tudinal anastomoses, and the anterior one is prolonged into a common 

 papillary vulva, situated in the middle of the first abdominal segment 

 beneath a horny process.*"* . * 



7 Fan der Hneven, loc. cit. p. 21, PI. II. fig. 15, 

 PI. III. fig. 1 {Limulus). 



8 There are two ovarian tubes, each continuous 

 posteriorly into a short oviduct with Cyamus 

 i^Roussel de Fauz^me, loc. cit. p. 253, PI. IX. fig. 

 19), with Je^a {Ratliki, Nov. Act. Nat. Cur. XX. 

 p. 32, Tab. VI. fig. 17), and with Mysis (^Frey, 

 loc. cit. p. 25). The two oviducts meet in a com- 

 mon vulva in front of the anus with Bopyrus and 

 Phryxus {Rathki, De Bopyro, &c., p. 19, Tab. I. 

 fig. 7, and Nov. Act. Nat. Cur. XX. p. 47). With 

 the Asellina, the ovarian tubes are coecal at both 

 of their extremities ; the oviducts pass off laterally 

 and open in the articulation of the fifth and sixth 

 segment of the body {Brandt, Mediz. Zool. II. p. 

 76, Taf. XV. fig. 32). I have observed an analo- 

 gous structure in the genital organs of Idol/tea 

 iMüller''s Arch. 1837, p. 434). With Caprella, 

 the ovarian tubes are coecal in the same way, but 

 they interanastomose by two pairs of short, trans- 

 versal oviducts {Goodsir, Edinb. New Philos. .Jour. 

 July, 1842, p. 184, PI. III. fig. 2). This author 

 adds, contrary to all analogy, that these oviducts 

 terminate in two vulvae situated one behind the 

 other on the middle of the belly. 



9 The incubating sac of Cyamus and Caprella 

 is composed of four Jamellae situated back of the 

 brancliiae upon the two footless segments of the 

 body {Roussel de Fauzime, loc. cit. ]). 249, PI. 

 Till. fig. 3, and Guodxir, loc. cit. p. 105, PI. III. 

 fig. 3, 10). With My.iis, this cavity contains also 

 only four lamellae covered with still bristles and 

 attached to the coxae of tlie last two pairs of feet 

 (Müller, Zool. Uanic. Tab. LXVI.fig. 1,2 ; Milne 

 Edwards, Hist. d. Crust. PI. XXVI. fig. 8, d.; 

 and Ralhki, in Wie!;mann\s Arch. 1839, I. p. 

 199). With Nerocila, there are also four large 

 lamellae arising from the coxae of the sixth and 

 seventh pairs of feet. With Idothea, the Aselli- 

 na and the Gammarina, on the other hand, the 

 fixe anterior segments of the body liave as many 



pairs of ventral lamellae of this kind. With Gam- 

 marus, the borders of these ten lamellae are cov- 

 ered with long bristles {Zenker, loc. cit. p. 8, fig. 

 N. b.). With Cymotlina, the coxae of the first six 

 pairs of feet liave a semilunar lamella {Milne 

 Edwards, Ann. d. Sc. Nat. III. 1835, PI. XIV. 

 fig. 2, and Cyclop, loc. cit. p. 784. fig. 436). The 

 same is true of Anilocra, judging from Savi^ny's 

 figure (loc. cit. Crust. PI. XI. fig. 10-). With 

 Bopyrus, and Phryxus, the incubating sac con- 

 tains six pairs of lamellae which, in the first of 

 these genera, are not wholly superposed {Rathki, 

 De Bopyro, &c., p. 6, Tab. I. fig. 5, and Nov. Act. 

 Nat. Cur. XX. p. 44, Tab. II. fig. 12). The sixth 

 or anterior pair of these lamellae is wanting with 

 Cepon {Duvernoy, Ann. d. Sc. Nat. XV. 120, PI. 

 IV. fig. 2), but with the Bopyrina in question, is 

 singularly attached to the head. According to 

 Treviranus (Verm. Schrift. I. p. 61, Taf. IX. fig. 

 52), there are at the bottom of this sac with 

 Ouiscidae, four short conical processes which se- 

 crete a yellowish fluid; but örandf (loc. cit. II. 

 p. 72, Taf. XII. fig. 2, Taf. XV. fig. 331 was una- 

 ble to find them, while Ratlike (loc. cit.) has been 

 led to regard as secreting organs also, two fila- 

 ments which, with Mysis, are attached to the ven- 

 tral wall, and stretch into the incubating sac. 



10 This origin and disappearance of the incubat- 

 ing lamellae I have seen very distinctly with Ido- 

 thea entomon {Müller\<! Arch. 1837, p. 435). The 

 females of Cyamus which Mailer (Zool. Danic. 

 Tab. C.XIX. fig. 16), and Treviranus (Verm. 

 Schrift. II. Taf. I. fig. 2). have figured, appear to 

 liave been individuals whose incubating sac was 

 not then fully develo])ed. 



11 The ovaries oi Sijuilla are so intimately blend- 

 ed in jiart with the liver, that they may be easi- 

 ly confounded with that organ. It is on this 

 account that Diivernoy''s figure (Ann. d. Sc. Nat. 

 VI. 1836, p. 24H, PI. XV. and VIII. 1837, p. 42, 

 PI. II.) of this organ with this same animal, is not 



