REPORT ON THE CIRRIPEDIA. 55 



Conchoderma. 



1. Filaments attached to the pedicel of the second cirrus, capi- 



tuluni with two tubular ear-like appendages, scuta 



bilobed, ... . Conchoderma auriturn, Linn., sp. 



2. No filaments attached to the pedicel of the second cirrus, 



capitulum without tubular ear-like appendages, scuta 



three-lobed, ...... Conchoderma rirgntiim, Spengler, sp. 



Conchoderma virgatum, Spengler, sp. 



Lepas virgata, Spengler, Skrifter Naturh. Selskab. I. 1790, Tab. vi. fig. 9. 

 Conchoderma virgata, Darwin, Lepadidre, 1851, p. 146. 



Of this species Darwin gives the following definition, which I think is quite sufficient 

 to characterise it : — Scuta three-lobed ; terga concave internally, with their apices slightly 

 curved inwards ; carina moderately developed, slightly curved ; peduncle blending into 

 the capitulum. No filament attached to the pedicel of the second cirrus. 



I do not wish to add anything to the very detailed description which Darwin gives of 

 this species. To make a comparison of this species with the variety chelonophilus 

 possible, I made a preparation of the parts which constitute the mouth. Of the maxillaj 

 Darwin says that they have five steps ; sometimes each step commences with a spine 

 rather larger than the others ; at the upper angle there are two large unequal spines 

 (neither pectinated), with a third, longer and thinner, situated a little below. That the 

 large spines of the upper angle are not pectinated has been pointed out by Darwin, as it 

 furnishes a remarkable difference from the spine of the maxilla of Conchoderma auriturn. 

 I am obliged, if not to deny the value of this characteristic, at least to diminish it. When 

 studied with an ordinary pocket lens the same spine appears in Conchoderma virgatum 

 to be distinctly pectinated near its base. 



Two specimens of this species were taken from the screw of the Challenger at St. 

 Vincent, Cape de Verdes, on the 25th April 1876, on the ship's voyage homeward. 

 According to Darwin, the growth of this species is very rapid. 



Conchoderma virgatum, var. chelonophilus, Leach (PI. II. figs. 13-15). 



Conchoderma virgata, var. chelonophilus, Leach, Darwin, Lepadidoe, 1851, p. 151. 

 Though the capitulum of this form differs considerably in appearance from that of the 

 common Conchoderma virgatum, Darwin regards it only as a variety of that species. This 

 he does because all parts of the animal, and especially the mouth and the cirri, are 

 quite identical in the species Conchoderma virgatum, and in the present form. Perhaps, 

 Darwin says, this variety may turn out to be a true species; but as our knowledge since 

 Darwin published this supposition has been almost stationary, I think it safest to follow 

 his example. However, I am willing to confess that, if no intermediate forms exist, in 



