478 DISCOVERY REPORTS 



Both Klie (1929) and Miiller (1927) describe various glands as excretory organs in 

 marine Ostracods. Thus they both describe two rudimentary "nephridia" as occurring 

 at the bases of the second and third pair of walking legs of Paradoxostoma. But there 

 is no evidence at all that any of these organs, which are probably ectodermal glands, 

 are even excretory in function, let alone serially homologous with the established seg- 

 mental excretory organs of other Crustacea. 



By the term "segmental excretory organ" I do not mean to imply that I know such 

 a structure to be definitely excretory in function. It is a morphological term which has 

 acquired a definite meaning. It implies in the Arthropoda a structure, segmental in 

 value, which exhibits an end sac and a duct leading to the exterior, or else an organ 

 about which there is definite evidence to indicate that it arose from such a structure. 

 Further, in the Crustacea, it has never yet been shown that such organs occur in segments 

 other than the antennal and maxillary and, hence, in this group, there is additional need 

 for caution in describing organs as segmental excretory organs outside these segments. 



In the Cypridinids no organ has ever before been described which, on the grounds 

 I have just explained, could be homologized with the segmental excretory organs of 

 other Crustacea. In Doloria, however, I have found a typical antennal gland and, 

 although I have not examined my sections fully, the same gland occurs in Gigontocypris . 

 Thus, in the Cypridae, there is a larval antennal gland and a maxillary gland in the 

 adult. In the Cypridinidae there is an antennal gland in the adult and there is no trace 

 of maxillary gland. 



The antennal gland occurs in the posterior part of the basis of the antenna (Figs. 11, 

 12), close behind the antennal basal ganglion. The duct opens to the exterior by a minute 

 pore at the postero-lateral angle of the joint. It broadens out as it passes forwards and 

 then turns sharply upwards along the anterior face of the end sac. It is apparently 

 intra-cellular, as I could only find three nuclei which were definitely in its walls. The 

 lumen is, however, wide and the walls consist of a vacuolated outer layer separated 

 sharply from an inner homogeneous or striated layer. The walls exhibit the same general 

 appearance that I described for Estheria (1924) and figured for Chirocephalus (1926 b, 

 Plate 22, fig. 2). 



The entrance of the duct into the end sac is guarded by a muscular sphincter valve. 

 The myofibrils are very distinct, but I could not be quite certain as to the number of 

 cells forming the sphincter. I believe it is three, in which case it agrees with the similar 

 sphincter in the maxillary gland of Cypris (Cannon, 1925) and the antennal gland of 

 Chirocephalus (Cannon, 1926 b). The lips of the sphincter bulge into both end sac and 

 duct, but most markedly into the latter (Fig. 12). In section it appears similar to the 

 valve which we described in Anaspides (Cannon and Manton, 1927, Fig. 3) and which 

 Vejdovsky (1901) described in Niphargus and Gammanis. 



The end sac shows the typical structure for a segmental excretory organ. It consists 

 of a thin-walled sac lying dorsally like a saddle across the duct. The cells constituting 

 its walls are vacuolated on their inner faces, and contain a layer of spherical bodies in 

 their outer layer which stain dark red in Mallory. 



