88 



CRUSTACEA — CIRRIPEDIA 



S- 



FiG. 57. — Conchoderma vir- 

 fjata, X 1. C, Carina 

 S, sciituiu ; T, terguiu 

 (After Darwin.) 



of them, e.g. Oxynaspis, live at considerable depths attached to 

 -p corals, etc., but large numbers Hoat on the 



surface of the sea, fixed often on log's and 

 wreckage of various kinds. Divhelaspis 

 is found attached to the shells of large 

 Crustacea. 



Conchoderma is an interesting genus, 

 the species of which live affixed to various 

 floating objects, the keels of ships, etc. ; 

 the mantle is often brilliantly coloured, 

 as in C. rirgata, and the skeletal plates 

 are reduced to the merest vestiges, leaving 

 the greater part of the hodj fleshy. 



Fam. 3. Tetraspidae. — This family 

 includes the single genus Jbla (Fig. 58), 

 which possesses only four skeletal plates, 

 a pair of terga and of scuta, coloured 

 blue, while the j)eduncle is covered with 

 brown spines. There are only two very 

 similar species known, /. cumingii, which is found attached to the 



peduncle of PoUicipes 



onitella, and /. qua- 



drivalvis, living on 



masses of tlie Siph- 



onophore Galeolaria 



decumheris. These two 



species are (j^uite differ- 

 ent in tlie partition 



of the sexes. In /. 



cuniingii tlie large 



individuals of normal 



structure are females, 



inside the mantle- 

 cavities of which are 



attached dwarf males 



of the form shown in 



Fig. 59. 



These (.irganisms 



liave the peduncle 

 buried completely in the substance of the female's mantle, inside 



Fio. 58. — Ihia enmuigii, 

 ? , X 1. ,S', Scutum ; 

 T, terguin. (After 

 Darwin.) 



M 



Fia. 59. — Ibla cumingii, dwarf 

 male, x 32. ^-1, Antennae ; 

 i', part of male imbeddeil 

 in tlie female, to wliieh the 

 torn niemlirane M belongs ; 

 K, eye ; Tli, thoracic ap- 

 ]iendages or cirri. (After 

 Darwin.) 



