Studies on marine Ostracods 557 



masticatory process, the pars incisiva. The latter part, which is in most cases bounded off 

 from the dorsal insertion part by a slight contraction, is bent somewhat inwards, so that these 

 processes on the right and the left mandibles are situated about opposite and rather near to each 

 other, close to the mouth when these limbs are in a position of rest. The basale, which is rather 

 moveably united to thecoxale, is always large and powerfid, rather elongated and, like the follow- 

 ing joints, strongly compressed from the sides. Proximo-ventrally it is drawn out into a very 

 powerful, broad, flattened masticatory process, which is cut off transversally distally and which 

 covers the pars incisiva on the coxale from outside almost like a shovel. The distal edge of this 

 masticatory process, which extends in most cases a short distance beyond the pars incisiva 

 on the coxale, is armed with a row of teeth. (As G. 0. Sars pointed out in his work of 1887, 

 p. 74, the masticatory process on the basale seems to have the same function as the cutting 

 part on the mandible in many other Crustacea, while the pars incisiva on the coxale serves as 

 a sort of tuberculum molare to break up the food more finely. The latter process seems, however, 

 also to serve partly as a cutting organ.) For the relation of the position of the masticatory processes 

 on the coxale and basale to the atrium see G. W. Ml'lleh, 1894, p. 48, pi. 1, fig. 19, pi. 40, 

 fig. 66. An epipodial appendage is developed fairly often; it is moderately large 

 or else small, with only one or two bristles (it never functions as a vibratory plate?); it is always 

 situated on the medial side of the basale, more or less proximally on the joint. The e x o p o- 

 d i t e is sometimes represented by a small, verruciform, unjointed process with or without 

 a single plumous bristle or else only by a single plumous bristle. It is situated dorso-distally 

 on the basale, most frequently somewhat medially and somewhat proximally of the distal 

 boundary of this joint. It never seems to be quite absent. It does not contain the exits of any 

 glands (as in the Cypridiniformes) and never seems to serve as a vibratory plate. The e n d o- 

 p o d i t c is always powerful and three-jointed, and forms a distinct, ventrally open knee together 

 with the protopodite. '* 



Maxilla: — This varies rather slightly in this group. It is developed as a masticatory 

 organ, comparatively short and powerful and with a powerful musculature. It consists of a 

 three-jointed protopodite and a two-jointed endopodite; the e x o p o d i t e 

 and the epipodial appendage are always quite absent. A\Tien in a position of 

 rest this limb is situated as follows: The protopodite points forward and somewhat outward, 

 the first joint of the endopodite points rather decidedly downward, there is a bend chiefly 

 between the coxale and the basale; the first endopodite joint is twisted so that its greatest 

 breadth almost coincides with the longitudinal axis of the body; the end joint points back- 

 ward and downward or almost straight backward. Protopodite: This is comparatively 

 short and thick. Its three joints are always well defined and are moveably joined to one 

 another; the basale is moveably joined to the endopodite (both the coxale and the basale 

 as well as the first endopodite joint are moved by special muscles). The procoxale and 

 the coxale are comparatively large and powerful, the former being in most cases somewhat larger 

 and stronger than the latter; the basale is rather considerably smaller than the procoxale and 

 is moderately strong. The procoxale and the coxale are each armed with an endite. These 

 endites are rather large and powerful, immoveably joined to these joints, flattened and armed 



