^ 294. THE CRUSTACEA. 361 



verse anastomoses. In front, the testicular vesicles are lost in these canals, 

 which finally diverge from each other in an arcuate manner, as is also true 

 of the Vas deferejis of the Glomerina. In this manner, these canals, as 

 two Ductus ejaculatorii, extend to a triangular scale situated under the 

 third thoracic segment, and terminate at the lower angles of this scale in 

 two short, conical, penis-like protuberances. '-'^ 



With the Chilopoda, the male organs are very complicated and formed 

 upon a wholly different type. Their orifices are always situated at the 

 posterior extremity of the abdomen. With some species, there is only a 

 single, long, testicular tube into which pass two lateral, also very long, coe- 

 cal tubes {Epididymes ?). At their point of junction, arise two short Vasa 

 deferentia, which terminate in a common, short, campanulate penis. Other 

 Chilopoda have two to three varicose testicular tubes which anastomose, 

 loop-like, at both of their extremities, and terminate, at last, in a longer or 

 shorter Vas defere7is, which bifurcates in its course, but its branches come 

 together again in a short penis. With all the Chilopoda, the common geni- 

 tal orifice is connected with the short excretory ducts of two to four oblong 

 accessory glands, the nature of which is yet unknown. '^^> 



§ 294. 



The Development of the Crustacea occurs, as with all Arthropoda, ac- 

 cording to a special type.^" 



After the disappearance of the germinative vesicle, a partial segmentation 

 occurs upon a given point of the surface of the vitellus. By this process, a 

 transparent, finely-granular, proligerous disc is formed.'-' The borders of 

 this disc gradually extend over, and finally cover the surface of the vitel- 

 lus. It is then changed into a proligerous vesicle enclosing the remainder 

 of the vitellus. 



At the pole of the egg where the proligerous disc is first formed, are de- 



25 For the male organs of the Chilognatha, see pedunculated vesicles {Vesiculae seminale.t). The 

 Newport, Philos. Trans. 1842, loc. cit. p. 99 ; posterior extremity of these testicles is continuous 

 Rymer Jones, Cyclop. III. p. 551, fig. 314; and into two Fasa deferentia which become dilated 

 Stein, in Mu/ler''s Arch. 1842, p. 246, Taf. XII.- into as nvAuy Ductus ejaculatorii. Perliaps this 

 XIV. (Julus, Polydesmus, and Glnmeris). The abnormal organization of these animals in this re- 

 two testicles of Glomeris were formerly described spect, will be reduced from further researches to 

 as ovaries by Brandt ; see his Beitr. loc. cit. p. the type of the Scolopendra. 



325, Taf. XII. fig. 8 ; but he has rectified this in his 1 The embryology of Crustacea has been brought 

 Recueil, loc. cit. p. 157. For the copulatory out, especially by the numerous and exact re- 

 organs of the Julidae, may be cited, also, the re- searches of Rathki ; see his Untersuch. iiber d. 

 searclies of Latreille, and Savi (loc. cit.). Bild. U; Entwickel. d. Flusskrebses, 1829, then his 



26 Lithobius has only a single testicular tube notes in Burdack^s Physiol. II. 1837, p. 250 ; his 

 with two epididymes and four accessory glands Abhandl. zur Bild. u. Entwickel. d. Mensch. u. d. 

 (Treviranus, Verm. Schrift. IL p. 25, Taf. V. fig. Thiere, 1833 ; his Mittheilung. iiber d. Entwickel. 

 7 ; L. Dufour, loc. cit. p. 87, PI. V. fig. 2, 3, and d. Decapoden, in Muller''s Arch. 1836, p. 187, or 

 Stein, loc. cit. p. 240, Taf. XII. fig. 1). Geophi- in Wiegmann''s Arch. 1840, 1, p. 241 ; and in the 

 lus has three interanastomosing, varicose testicles, Neuest. Schrift. d. Danzig, naturf. Gesellsch. III. 

 and two accessory glands {Stein, loc. cit. p. 243, Heft. IV. 1842, p. 23 ; then, Zur Morphol., Reise- 

 Taf. XII. fig. 7). Judging from Muller^s figure bemerk. aus Taurien, 1837 ; his Beobacht. u. 

 (loc. cit. Taf. II. fig. 5), Scolopendra morsitans Betracht. iiber d. Entwickel. d. Mysis vulgaris, in 

 li:is also two anastomosing varicose testicles. But Froriep''s neue Not. XXIV. 1842, p. 181 ; and 

 tliis point is made somewhat uncertain from the finally his Comment, de Animal. Crust, generat. 

 researches oi Kutorga (loc. cit. p. 10, Tab. II. fig. 1844. See, also, Erdl, Entwickel. d. Hummereies, 

 4-6), who has shown positively the existence of four 1843 ; and Joly, Sur le developp. des Caridina, in 

 accessory glands with this animal. L. Dufour''s the Ann. d. Sc. Nat. XIX. loo. cit. p. 57, PI. IV. 

 figures (loc. cit. p. 97, PI. V. fig. 5) of the male 2 Cajbcer maenas forms perhaps the only ex- 

 organs of 5c«/i§'ero indicate here a very difi'erent ception in this respect. Here, the segmentation ap- 

 organization. There are two testicular tubes which pears to t)e complete ; see Rathke, in Froriep's 

 unite loop-like at the anterior extremity and then neue Not. loc. cit. p. 182 ; and Erdl, loc. cit. p. 

 send oil' a long very flexuous canal which has two 27. 



31 



