THE APPENDAGES IN OTHER HALOCYPRIDIDAE 321 



been moved back clear of the labrum, the maxillulary endites could, with their strong spines, grip 

 it and probably to some extent crush it. A forward and upward thrusting of the endites would 

 progressively move the prey through the oral atrium into the mouth. The angle at which the oeso- 

 phagus leaves the oral atrium is of importance, in that there is no hindrance to direct passage of food 

 into it. During transport of prey into the oral atrium, it would be subjected to further crushing by 

 the coxal gnathobases of the mandibles, while the four posterior molar spines would aid transport by 

 gripping the prey during the recovery movement of the maxillules. 



It has been noted that the portions of larger copepods contained in the stomachs of Conchoecia are 

 of such a size that they would just pass between the bases of the limbs and into the oral atrium, but 

 the large specimens from which they are derived will not be able to pass. Each must be held below 

 the level of the labrum mainly by the mandibular palps. The incisor edges of the mandibular bases 

 could then shear portions, particularly limbs, from the prey. The slight rotation of the coxa, necessary 

 to carry out this process, and the slight downward movement of the apices of the bases, would not 

 prevent the palps from continuing to hold the prey in position. The secretion of the anterior labral 

 glands could then entangle portions broken free and simplify their retention by the appendages. 

 Further transport of these fragments probably resembles that of small whole prey. 



THE APPENDAGES IN OTHER HALOCYPRIDIDAE 



In order to add to the overall picture of the Halocyprididae it is of interest to compare the appendages 

 of Conchoecia with those of other genera. A detailed comparison must, however, be postponed until 

 more species of these other genera have been studied. Some characteristic features, however, may be 

 considered. In Euconchoecia and Archiconchoecia, particularly, the setation of the antennule and 

 the secondary sexual characters of the antennal endopod of the male differ from those of Conchoecia 

 but, apart from differences of the mandibular gnathobases and the enormously elongated terminal 

 setae of the male first trunk-limb of Euconchoecia, the remaining appendages are closely similar in 

 structure and interrelation in all genera. Of particular note is the fact that the mandibular coxa has 

 an articulation with the labrum similar to that described on page 307 in Conchoecia. Not only does this 

 show a functional similarity in the mandible, but it also provides a new taxonomic character common 

 to the genera. 



Among the halocyprid genera, differences may be seen in the structure of the molar surface of the 

 mandibular coxa. Skogsberg (1920, p. 740) questioned the homologies of the masticatory pad and 

 the oval cavity on the coxa of Euconchoecia. In Conchoecia, the molar pad is in fact situated in a slight 

 depression, though this is less marked than the depression in the coxa of Euconchoecia. The main 

 differences between this latter genus and Conchoecia would appear to be as follows. In Euchonchoecia 

 the small sharp conical bristles of the central and proximal parts of the molar pad are absent. On the 

 posterior and oral surface of the molar surface of the coxa, there are up to twelve or thirteen molar 

 claws instead of only four as in Conchoecia. The marginal bristles are much less dense and the orally 

 directed group seems to be absent. These latter are functionally replaced by the more proximal 

 marginal claws. Skogsberg further pointed out that the claws can be folded inwards into the oval 

 depression. The functional significance of this is unknown, but may be some adaptation to the trans- 

 port of food in the oral atrium. The structure of the molar surface differs less in Archiconchoecia. The 

 molar spine (Miiller's spine 'D') is absent, and the molar claws and bristles are less well developed. 

 The structure of the molar surface in the genus Halocypris has been discussed by Skogsberg (1920). 

 In H. globosa it is very similar to that of Conchoecia. Halocypris brevirostris differs particularly in the 

 absence of marginal molar claws. The condition in other species of the genus has not been described. 



