56 LEPADIM1. 



swellings on the thorax and prosoma, and in others the fila- 

 mentary appendages : the testes seen in the apex in one of 

 these appendages in Conchoderma, is represented in PI. IX, 

 fig. 5. The two vesicular seminales are very large; they 

 lie along the abdominal surface of the thorax, and gene- 

 rally (but not in some species of Scalpellum) enter the 

 prosoma, where their broad ends are often reflexed ; here 

 the branched vessels leading from the testes enter. The 

 membrane of the vesicular seminales is formed of circular 

 fibres ; and is, I presume, contractile, for I have seen the 

 spermatozoa expelled with force from the cut end of a 

 living specimen. The two canals leading from the vesi- 

 cular generally unite in a single duct at the base of the 

 penis ; but in Conc/ioderma aurita, half-way up it. The pro- 

 bosciformed penis, except in certain species of Scalpellum, 

 is very long ; it is capable of the most varied movements ; 

 it is generally hairy, especially at the end ; it is supported 

 on a straight unarticulated basis, which in Ibla quadri- 

 valvis alone (PL IV, fig. 9 a), is of considerable length; 

 in this species, the upper part is seen to be as plainly 

 articulated as one of the cirri; in Alepas, the articula- 

 tions are somewhat less plain, and in the other genera, 

 the organ can be said only to be finely ringed, but these 

 rings no doubt are in fact obscure articulations. In the 

 females of Ibla Cumingii and Scalpellum ornatum, there 

 is, of course, no penis. 



Female Organs. — M. Martin St. Ange has described 

 how the peduncle* is gorged with an inextricable mass 

 of branching ovarian tubes, filled with granular matter 

 and immature ova. In Conchoderma and Alepas, the 

 ovarian tubes run up in a single plane (PI. IX, fig. 3,) 

 between the two folds of corium round the sack. Here 

 the development of the ova can be well followed : a 

 minute point first branches out from one of the tubes ; its 



* I may here mention, that in all sessile Cirripedes, the ovarian branching 

 tubes lie between the calcareous or membranous basis and the inner basal 

 lining of the sack, and to a certain height upwards round the sack : the true 

 ovaria and the two duels occupy the same position as in the Lepadidse. 



