284 LECTURE XIII. 



develope ova only, the spermatozoa being formed in distinct and 

 much smaller parasitic males. The same excellent observer has detected 

 similar parasitic individuals, mouthless and stomachless, containing 

 abundant spermatozoa, attached to the larger individuals, possessing 

 both male and female organs, of Ibla quadrivalvis, Scalpellum 

 vulgare, Sc. rutilum, Sc. rostratum, Sc. Peronii, and Sc. villosu?n, 

 such supplemental males having specific characters as distinct as 

 those of the hermaphrodite individuals to which they are attached, 

 and in which the vesiculas seminales are unusually small. 



The ordinary hermaphrodite combination of generative organs 

 prevails so far as is hitherto known in all the species of Lepas, Pceci- 

 lasma, Oxyiiaspis, Anelasma, Pollicipes, Lithotrya, Otion, and Cineras. 

 The male organs consist of two testes, two sperm-bladders with their 

 sperm-ducts, and the penis. The testes consist of minute compressed 

 seminiferous lobes, forming usually a leaden-coloured pyriform digi- 

 tate or dendritic mass : they coat the stomach, enter the pedicels and 

 basal joints of the cirri, in some genera occupy certain swellings on 

 the thorax and prosoma, and in others penetrate the filamentary 

 appendages. They are confined to the thorax and prosoma in the 

 sessile Cirripeds. The sperm-bladders are, in most species, very 

 large : in the Lepadoids they lie along, and, save in some species of 

 Scalpellum, penetrate the prosoma, where their broad ends are often 

 reflexed : here the branched ducts from the testes enter. The coats 

 of the bladder are formed of circular fibres, which Darwin concludes 

 are muscular, having seen the spermatozoa expelled with force from 

 the cut end of a living specimen. The sperm-bladders, as they extend 

 backwards, gradually contract to canals w^hich unite in a single 

 sperm-duct at the base of the penis, or, in Otio7i, half-way along it. 

 In the bell-barnacles {Balanus) the sperm-reservoirs are very long 

 and tortuous : they lie within the thorax and prosoma, and unite at 

 the base of the proboscidiform penis. This organ is of great length, 

 except in certain species of Scalpellum, and can move freely in all 

 directions ; it is supported on a straight unarticulated base, short in 

 most, but in Ihla qiiadrivalvis of great length*: the rest of the 

 extent is more or less distinctly articulated ; short hairs project from 

 the intervals of the rings, and more abundantly from the end of the 

 penis. 



In the Balanoids the ovaria consist of glandular bodies^ of un- 

 branched or main tubes, and of branching tubes and ca3ca. The 

 ovarian glands are situated near the basal edge of the labrum : the 

 branched tubes lie between the calcareous or membranous basis and 



* CCXXIII. p. 5G. pi. iv. fig. 9 a. 



