346 



THE CRUSTACEA. 



^287. 



a condition to respire atmospheric air.^' But with Tylos, this pulmonary 

 apparatus is still more highly developed ; for, under the four pairs of oper- 

 cula, there are, instead of simple branchial plates, oblong appendages on 

 which is a transverse row of aeriferous sacs having a kind of stigma on 

 their under surface/-' 



All the Myriapoda respire by true tracheae. Their blood does not 

 require, therefore, special organs to receive the influence of the air, for this 

 last is carried into every part of the body. 



The stigmata for the ingress and egress of the air, are easily seen with 

 the Chilopoda, for they are usually surrounded with a ring of brown chi- 

 tine, and situated on each side of the body between the base of the feet 

 and the dorsal shields; they are not found, however, above all the feet, 

 for the segments which have them alternate more or less regularly with 

 those that are without them.'"'' With the Chilognatha, the very small 

 stigmata are on the ventral surface. They are situated on the anterior 

 border of the ventral plates, from the posterior border of which arise the 

 feet.**' The intimate structure of these tracheae, which are usually brown, 

 is exactly like that of those of insects.''" Among the Chilognatha, the 

 Julidae are noticeable for the very simple character of their trachcan 

 apparatus. Each stigma leads into a tuft of tracheae from which arise 

 air-canals which neither ramify nor anastomose but gradually become 

 smaller and smaller and surround the various organs.'*" With the Glo- 

 merina, on the contrary, the tracheae, which arise from the stigmata by 

 two trunks, are branched, but do not anastomose with the neighboring 

 branches. ''^' Those of the Chilopoda most closely resemble those of the 

 Insecta, — being very ramose, and their large trunks intercommunicating 

 at their origin by longitudinal and transverse anastomoses, so that each 

 stigma can introduce air into the entire trachean system.'**' 



1 Accordina; to Duvernoy and Lerebou/let (loo. 

 cit. p. 231, PI. VI. fig. l4), these cavities secrete a 

 li(iuld for the raoisteiiiag of the braiicliiae. See 

 upon this subject, my observations in Mu/ler^s 

 Arch. 1842, p. 141, note 2. 



- See Savisni/, Descript. de I'Ksvpte, loc. cit. 

 PI. XIII. fig. I.''— 1.» ; but especially Milne Ed- 

 wards, Institut. 1839, p. 152, and llist. d. Crust. 

 III. p. 187, and his figures in the Iconograph. du 

 R^gne anim. Crust. PI. LXX. 



3 With Lil/ioOiu.s, there is a stigma above the 

 first, third, fifth, eighth, tenth, twelfth, and four- 

 teenth pairs of feet {Treviranus, Verm. Schrift. II. 

 p. 29, Taf. IV. fig. 7, Taf. VI. fig. 5). Witli Scolo- 

 pendra, the stigmata liave a similar disposition 

 (Kutori^a, loc. cit. p. 14). 



4 See Savi, Isis, 1823, p. 219, Taf. II. fig. 9, a. a., 

 and Burmeister, Ibid. 1834, p. 134, Taf. I. fig. 2, 



a. a. (Julus). These stigmata with Julus were 

 entirely overlooked by Treviranus. He had re- 

 garded as such the orifices of a row of glands 

 which are situated on the sides of the segments of 

 the body (Verm. Schrift. II. p. 42, Taf. VIII. fig. 

 4, S. S.). 



5 The characteristic spiral filament of the Insecta 

 is also not wanting here : see Kutorga, loc. cit. p. 

 14, Tab. II. fig. 8. 



6 Straus, Considcrat. &c. p. 307, and Burmeis- 

 ter, loc. cit. Taf. I. fig. 3 (Julus). 



7 Brandt, in Miiller's Arch. loc. cit. p. 323, Taf. 

 XII. fig. 4, 5 (Glomeris). 



8 Straus, loc. cit. p. 307, and Traits d'Anat. 

 comp. II. p. 161 ; Treviranus, Verm. Schrift. 11. 

 p. 30, Taf. VI. fig. 6 {Lithobius), and Mailer, 

 Isis, 1829, p. 551, Taf. U, fig. 1. 



