^^ 288, 28?. THE CRUSTACEA. 347 



CHAPTER VIII. 



ORGANS OF SECRETIOX. 



I. Urinary Organs. 



§ 288. 



As yet, Urinary organs have not been observed with the Crustacea 

 except in the Myriapoda. Here, as with the Insecta, they consist of long, 

 small, bi'ownish vessels, caecal, and describing many convolutions about 

 the stomach and intestine. These Malpighian vessels, as they have been 

 termed, open into the digestive canal at the boundary between the stom- 

 ach and intestine, and secrete as certainly as do those of the Insecta, uric 

 acid.*^' With the Chilopoda, thei-e is usually one on each side of the 

 pylorus ; but with the Chilognatha, there are two, which open, however, 

 into the intestinal canal by a common orifice/-^ 



It is now undetermined whether these organs exist also in the other fam- 

 ilies of Crustacea. But with some Decapoda, there are certain caecal 

 vessels which are imperfectly known. They open into the intestine at 

 various points between the pylorus and rectum, and a more complete 

 examination may, perhaps, show them to be of a urinary nature. ^'^^ 



II. Organs of Special Secretions. 



§ 289. 



The Astacina have a very remarkable secretion commonly known as 

 Crabs-eyes. These are a kind of calculi composed of carbonate of lime 



1 For the Malpighian vessels, which were for a 67S) is very common with the Macrura, Brachyura, 



long time regarded as biliary canals, see further and Anomura, and notably with Astacus fluvia- 



iinder the anatomy of the Insecta. tilis, Homarus marinus, Cancer pagurus. For- 



'i Ramdohr, Abhandl. über d. Verdauungsw. tu nus pn her, vmA Cancer maenas. But although 



&c. p. 149, Taf. XV. fig. 1 (Julus) ; Treviranus, Milne Edwards admits the same also (loc. cit. I. 



Verm. Schrift, loc. cit. p. 24, 44, Taf. V. fig. 4, Taf. p. 76), yet it does not appear to be agreed upon, for 



Till. fig. 6 (Lithobius and Julus), and L. Du- Meckel (Syst. d. vergleich. Anat. IV. p. 161) con- 



/our, Ann. d. Sc. Nat. loc. cit. p. 86, 96, PI. V. tradicts Cuvier in this respect, and declares that 



fig. 1, 4 {Lithobius and Scutisrera). Scutigera he has never found this caecimi either with the 



differs from the other Chilopoda in having two Crabs or with Astacus, Scyllarus, and Palinu- 



pairs of urinary canals. rus, but only with Pagurus, Penaeus, and 



See also Kutorga, loc. cit. p. 6, Tab. I. fig. 2, PalaeTUon. Duvernoy, also (Le(jons d'Anat. 



and Müller, Isis, 1829, p. 550, Taf. II. fig. 5 Comp. V. p. 228), has not observed it in the Ma- 



{Scolopendra) ; finally Brandt, in Muller^s Arch, crura just cited, nor with Galathea squa- 



loc. cit. p. 322, Taf. XII. fig. 2 {Glomeris). mi/era, and Palaemon serratus, although he 



3 Swammerdamm (loc. cit. p. 87, Taf. XI. fig. 3) perceived it with Portunus puber directly behind 



had already figured, with Pagurus, a pretty long the pylorus, and with Cancer pagurus, near the 



coecum opening at the posterior extremity of the rectum. Like Milne Edwards (Hist. d. Crust, 



intestine. With Mala squinado, there are three I. p. 115, PI. X, fig. 2, j. (Maia)), I must leave un- 



such pretty long, of which two are inserted on each determined the point whether or not, this glandular 



side of the pylorus, and the third a little further mass which, with the Decapoda, is concealed under 



behiiKl (Milne Edwards, Hist. Nat. d. Crust. I. the floor of the respiratory cavities in the bottom 



p. 76, PI. IV. fig. 1, m. n.). Lund (Isis, 1829, p. of the cephalothorax, and which opens externally 



1302) has also seen two glandular canals rolled up by an excretory canal between this same cephalo- 



in a knot, which open each side of the pylorus, thorax and the first abdominal segment, — ia 



while a third entered the rectum. This last, ac- really a urinary organ, 

 cording to Cuvier (Lecjons d'Anat. Comp. III. p. 



