642 Brady and Norman — Monograph of the Marine and Freshwater Ostracoda 



and thumb of which are very strong, forming a grasping organ, the inner edge 

 of the lower claw being finely serrated. 



The first maxillae are furnished with three seta- or spine-tipped lateral lobes, 

 and a terminal, usually two-jointed, palp (PI. liii., fig. 5). The first joint of the 

 palp is usually of some length, the last short, bent inwards, and ending variously 

 in set£e, spines, and ungues. 



The second maxillse are always furnished outwardly with a semi-elliptic, 

 thin, vibratory lamina, set all round with long, plumose setae. The limb itself 

 attains its maximum development in Ct/pridina and Crossophorus (PI. liii., fig. 6), 

 and consists of three small lobes fringed with sjjiniform setae of varied structure, 

 followed by a fourth lobe which, besides setae, is armed with a series of five or 

 six teeth, overlying each other, the uppermost being the largest. The teeth 

 (PI. LIII., fig. 6 6) are narrow, upright, slightly curved at the tip, and strongly 

 denticulated on the inner edge. Beyond this tooth lobe a fifth may be made 

 out, which is edged with stiff spine-like setae, many of which are serrated at 

 the edge. Beyond this again is a three-lobed palp, each lobe ending in setae. 

 In other genera several of tliese lobes are difiicult to distinguish, or altogether 

 absent, and the palp, though always present, is sometimes represented by 

 only one lobe. But it is desirable to notice the teeth further, for they have 

 every appearance of being really teeth, and often of powerful structure for use 

 in mastication, and the exact form of these teeth is very characteristic of 

 different genera. In Philomedes the outermost tooth is wide at the base, 

 somewhat triangular, and smooth on the edge ; the teeth, however, which 

 underlie this are denticulately edged. In Tetragonodon (PI. lviii., fig. 6) the 

 tooth is of very large size, occupying the greater part of the end of the 

 member, subquadrate in form ; broadly truncate at the end and smooth-edged. 

 In Paramekodon (PI. lix., fig. 8) it assumes the shape of a long oblong, the long 

 side being uppermost ; at one end of this oblong rises a fang-like elevation, 

 smooth on the edge, and at intervals beyond this the tooth-plate give out three 

 processes, each cleft at its apex into two, three, or four points. In Butiderma 

 (PI. LVIII., fig. 15) the tooth is trifid, with smooth edges. In Sarsiella there are 

 no teeth, or even spine-like setae, but only ordinary setae on the limb. 



The third maxillae, when most fully developed, as in Crossophorus (PI. liii., 

 fig. 7) and Cypridina^ consist of four small, seta-bearing lobes, behind which is a 

 triangular seta-edged, thin, vibratory lamina. The organ in other genera becomes 

 more and more simplified, until in Sarsiella the vibratory lamina and the lobes 

 are all represented by a single lobe. 



The vermiform appendage is very constant in general character, tlie chief 

 difference being found in the exact structure of the terminal lips. 



