44 LEPADID.E. 



villosum ; they consist of a very small single segment, 

 destitute of spines in Lepas, and spinose in Psecilasma, 

 Dichelaspis, Oxynaspis, Scalpellum, and some species of 

 Pollicipes ; they consist of several segments in Alepas, 

 Ibla, Lithotrya, and in some species of Pollicipes. In the 

 latter genus, some species have their caudal appendages 

 multiarticuiate, though so obscurely articulated, that the 

 passage (fig. 22) from several to one segment is seen to 

 be easily effected. When the appendage consists of many 

 articulations, it is generally about as long as the pedicel 

 of the sixth cirrus; but in Ibla quadrivalvis, it is four 

 times as long. The segments are narrow, slightly flat- 

 tened, much tapering; each (fig. 24) is surmounted by 

 a ring of short spines, which are generally longest on 

 the apex of the terminal segment. I could never trace 

 muscles into these appendages. 



Alimentary Canal. — The oesophagus is of considerable 

 length : it is formed of strong, transparent, much folded 

 membrane, continuous with the outer integuments, and 

 moulted with them : it is surrounded by corium, and as 

 already stated, by numerous muscles : at its lower end it 

 expands into a bell, with the edges reflexed, and some- 

 times sinuous : this bell lies within the stomach, and 

 keeps the upper broad end expanded. According to the 

 less or greater distance of the mouth from the adductor 

 muscle, the oesophagus runs in a more or less parallel 

 course to the abdominal surface between the first and suc- 

 ceeding pairs of cirri, and enters the stomach more or less 

 obliquely. In Ibla alone, it passes exteriorly to, and 

 over the adductor scutorum muscle. The stomach lies 

 in a much curved, almost doubled course ; it is often a 

 little constricted where most bent ; it is broadest at the 

 upper end, and here, in Lepas and Conchoderma, there 

 are some deep branching caeca; in the latter of these 

 two genera, the whole surface is, in addition, pitted in 

 transverse lines. The stomach is coated by small, 

 opaque, pulpy, slightly arborescent glands, believed to be 

 hepatic; these are arranged in longitudinal lines, in all 



