332 



THE CRUSTACEA. 



^ 280. 



§ 280. 



A large portion of the Crustacea have glandular appendages to the 

 digestive canal. But it is only a few of these organs to which can be at- 

 tributed the function of Salivary Glands. Two such of a lobular form, 

 are found in the Cirripedia on the stomach, and pour their secretion into 

 the anterior part of this organ.''* 



But with the Myriapoda, these organs are very distinct. There are 

 two or more on each side of the oesophagus and stomach, and their rather 

 long, excretory ducts open into the oral cavity.'-' With all the other 

 Crustacea, these organs are wholly wanting.* 



The Liver, which exists sometimes as a glandular layer enveloping the 

 digestive canal, and sometimes as a separate organ, is composed of green- 

 ish, or of yellowish-brown tubes of variable size, the walls of which are 

 formed by numerous granular cells, between which are interposed fat-vesi- 

 cles. <'^' With most of the lower Crustacea, with the Siphonostoma, the 

 Lophyropoda, the Phyllopoda, and Myriapoda, the liver is not isolated 

 from the digestive tube, but the follicles of its glandular layer are some- 

 what protuberant on the external surface of this tube, and open on its in- 

 ternal surface, each probably by a separate orifice.'^* With Argulus, 



1 See Cuvier, Mem. kx;. cit. p. 10, fig. 9, u. u., 

 11. d. (Lepas) ; Btirmeister, loc. cit. p. 42, Tab. 

 II. fig. 13, 1-t, c. (Coroiiula) ; Karsten, Nov. Act. 

 Nat. Cur. XXI. Tub. XX. fig. 1, d. (Balanus). 



2 With Lithobius, and Scutigera, there are 

 two compact salivary glands which extend from 

 the head into the first segments of the body (L. 

 Dufour, loc. cit. p. 83, 95, PI. I. V.). Trevi- 

 ranus (Verm. Schi'ift. II. p. 25, Taf. V. fig. 4, q. q.) 

 regarded them as a mass of fat. The botryoidal 

 glands, which open by several excretory ducts into 

 the oral cavity, have been observed by Gaede 

 (JViedemann's zool. Mag. I. p. 107, Taf. I. fig. 7, i 

 i.), by MuLler (Isis, 1S29, Taf. II. fig. 5), and by Ku- 

 torga (loc. cit. p. 4, Tab. I. fig. 4), in the anterior 

 extremity of the body of Scolopendra. With 

 Glomeris, there are only two short, slightly flex- 

 uous glandular tubes situated in tlie lower portion 

 of the head and opening into the mouth {Brandt, 

 in Miiller's Arch. 1S37, p. 323, Taf. XII. fig. 3). 

 With other Myriapoda, these organs quite resemble 

 those of the Insecta. Thus, with Geophilus, there 

 are two flexuous tubes situated pretty far behind the 

 head, and from which pass off two very long, small 

 excretory ducts along the oesophagus to the 

 mouth {Treviranus, loc. cit. p. 37, Taf. VII. fig. 



3). With Julus, the salivary organs are eveu 

 longer and form, with the urinary canals, a very 

 complicated net-work about the stomach, and from 

 which pass off, according to Treviranus (loc. cit. 

 p. 44, Taf. VIII. fig. 6), three excretory ducts to 

 the mouth. But Ramdohr (Abhandl. &c. p. 149, 

 Taf. XV. fig. 1, g. g.) has figured only two simple 

 salivary canals with Julus, and this number has 

 been verified by Burmeister (Isis, 1834, p. 136). 

 I have seen these two canals with Julus sabulosus 

 anastomose in an arcuate manner at then- posterior 

 extremity.* 



3 For the intimate structure of the biliary tubes, 

 see Schlemm, De hepate ac bile Crust., loc. cit. p. 

 14, Tab. II. fig. 1-8 {Astacus), and Karsten, 

 Nov. Act. Nat. Cur. XXI. p. 295, Tab. XVIII. 

 -XX. {Oniscus, Astacus, and Balanus). 



i An hejiatic layer of this kind may be observed 

 with the Penellina, Lernaeodea, Ergasilina (Jford- 

 mann, loc. cit. Taf. I.-X.), and with Artemia (Joly, 

 loc. cit. p. 239, PI. VIII. fig. 4). Tlie numerous 

 caeca, which, according to Rathke (Nov. Act. Nat. 

 Cur. XX. p. 122, Tab. V. fig. 15), belong to the 

 entire digestive canal of Chondracanthus, are 

 ])erhaps formed by an hepatic substance. With 

 the Chilognatha, and Chilopoda, I have found the 



* [ § 280, note 2.] For the salivary glands of 

 Julus see Leidy (A Flora and Fauna within Living 

 Animals, p. 17, PI. VII. fig. 21, a. b. In Smithson- 

 ian Contributions to Knowledge, V. 1853). Beside 

 the long tubular glands mentioned by the authors 

 above, he has described two others which are 

 placed on each side of the oesophagus and are 

 pyriform, conglomerate, and cellular in structure. 



Wright (Ann. Nat. Hist. 1848, p. 140) has also 

 made observations on the glands of Geophilus 

 which open into the head ; he has shown them to 

 be veneniferous, for a single excretory duct passes 

 off from the anterior part of this gland and termi- 



nates, on each side, in a canal of the jaw or mandi- 

 ble, as in the Arachniodae. — Ed. 



t [ § 280, Dana (Report, &c., loc. cit. p. 1339) 

 speaks of several small glands about the mouth, 

 and communicating with it by ducts, with the Cali- 

 goidea, and which are probably of a salivary 

 nature. These organs in Argulus have been care- 

 fully examined by Leydig (Ueber Argulus, &c., loc. 

 cit. p. 333, Taf. XIX. fig. 2, a.), and especially as 

 to their relations to the spicula (see § 278, note 6) 

 of these animals. Leydig thinks they may as 

 well be regarded poisonous as salivary glands. See 

 my note under § 278, note 7. — Ed. 



