-^ 294. TUE CRUSTACEA. 361 



Terse 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 deferens 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, 

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

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

 together again in a sho^t 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 segmentatiou 

 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 t?ie Chilognatha, see pedunculated vesicles (f^esiculae semmale.i). The 

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

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

 Stein, in Mü//er''s Arch. 1842, p. 246, Taf. XII.- into as many Ductus ejaculatorii. Perhaps this 

 XIV. (Julus, Polydesmus, and Glomeris). The alinormal 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 Sco/o^eMdra. 



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

 Kecueil, 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 Rathk^ ; see his Untersuch, über d. 

 ■searches of Latreilte, and Savi (loc. cit.). Bild. u. Entwickel. d. Flusskrebses, 1829, then his 



* Lithobius has only a single testicular tube notes in BnrdacK's Physiol. II. 1837, p. 250 ; his 

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

 iTreviranus, Verm. Schrift. II. p. 25, Taf. V. fig. Thiere, 1833 ; his Mittheilung, über d. Entwickel. 

 7 ; L. Da/our, loc. cit. p. 87, PI. V. fig. 2, 3, and d. Decapoden, in Midieres Arch. 1836, p. 187, or 

 ^tein, loc. cit. p. 240, Taf. XII. fig. 1). Geopki- in fViegmann^s Arch. 1840, 1, p. 241 ; and in the 

 las has three interaiiastomosing, 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 Taurieh, 1837 ; his Beobacht. u. 

 <loc. cit. Taf. II. fig. 5), Scolope.ndra morsiians Betracht, über d. Entwickel. d. Mysis vulgaris, in 

 has also two anastomosmg varicose testicles. But Froriep's neue Not. XXIV. 1842, p. 181 ; and 

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

 researches o( 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 Jo/y, Sur le developp. des Caridina, in 

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

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

 organs of Scutigera indicate here a very different ception in this respect. Here, the segmentation ap- 

 organization. There are two testicular tubes which pears to be complete; see Rathke, in Froriep\'! 

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

 .«end off a long very flexuous canal which has two 27. 



31 



