28 BRITISH COPEPODA. 



the nature of the appendages, by Thorell called the 

 first pair of maxillae, by Glaus the mandibles, to which 

 the palp-like organ is attached. 



In considering this question we shall do well to 

 take a somewhat wider survey than merely of the 

 order Copepoda. Among the nearly related order 

 Ostracoda, for the most part consisting of true 

 Gnathostomous Crustacea, we find a group, including 

 chiefly the genus Paradoxostoma, in which the mouth 

 is modified for suctorial purposes in a manner at once 

 reminding one of the siphonostomous Copepoda. In 

 Paradoxostoma the tubular mouth is formed by the 

 coalescence of the labrum and labium, and the man- 

 dible assumes the form of a stilet, having a very 

 slender filiform palp, the almost exact counterpart of 

 the same organs in A.contioplwrus , Cydopicera, &c. (see 

 PI. LXXXIX, fig. 4, and PL XC, fig. 4). There 

 can be no doubt, I think, that in the well-marked 

 siphonostomous Copepoda, such as Acontiophorus, Dys- 

 pontius, and Artotrogus (Ascomyzon), the tubular mouth 

 is formed, as in Paradoxostoma, by the union of the 

 upper and lower lips, and that the filiform organs lying 

 immediately by the side of the siphon (see PI. XC, 

 fig. 1 c, and PI. XCI, fig. 6 c c) are modified man- 

 dibles and palps; in Artotrogus, indeed (PL XCIII, 

 fig. 3 b &'), we find this stilet-shaped mandible dis- 

 tinctly toothed at its apex. In the genus Cydopicera, 

 of which I have fortunately collected and examined 

 many specimens with great care, all the mouth- 

 organs are largely developed; there is an unmistak- 

 able mandible with a well-developed palp, a distinct 



