4l6 HeiT B. Nfemec on Excretory Organs 



The excretory organs characteristic of the majority of 

 Crustacea, namely the antennary and shell-glands, are found 

 in the Oniscodere, which formed the greater part of my 

 material for investigation, either greatly reduced or with 

 altered functions, as has already been pointed out by Glaus 

 in the case of the Anisopoda. 



The antennary gland forms a small glandular saccule at 

 the base of the antennae, which, however, is destitute of any 

 efferent duct. In Asellus and Ligidium this saccule is of 

 fairly large size and also possesses a distinct lumen. In the 

 OniscinesR, on the other hand, the homologous rudiment forms 

 only a small solid mass of cells. Probably the saccule 

 alluded to corresponds to the so-called terminal saccule 

 (" Endsackchen "), as it appears in homologous normally 

 developed glands. 



The shell-gland, which was found by Glaus in Asellus and 

 certain Oniscinea^, exhibits various conditions in Isopods. 

 In Asellus, as stated by Glaus, and as I was able to convince 

 myself, it is enormously developed. In this case also it 

 really represents an excretory organ. In Oniscodege this 

 gland is either reduced, as is especially the case in the Onis- 

 cinese, or it has — in Hygrophileje — experienced a change of 

 function. 



In Ligidium, Haplophthalmus, and Trichoniscus this gland 

 appears as an organ of somewhat considerable size, which 

 extends beneath the masticatory stomach right into the basal 

 joints of the second pair of maxillce and of the maxillipedes. 

 In front there can be distinguished a thin-walled terminal 

 saccule, leading into a long coiled canal which opens on the 

 underside of the second pair of maxillaj. The epithelium of 

 the coiled canal possesses' a typical cortical striation, which is 

 coarsely developed, particularly in Haplophthalmus. Exactly 

 below the orifice the maxillipede exhibits a spoon-shaped 

 excavation, and it is in this very cavity that the discharged 

 secretion is collected. Sagittal longitudinal sections show 

 quite clearly that the secretion which fills the cavity really 

 comes from the shell-gland. 



This collection of the evacuated secretion must surely have 

 an object. Probably the secretion comes in some way into 

 play in the process of feeding. This explanation is the more 

 probable since otherwise no differentiated salivary glands 

 occur in Oniscodese, and, moreover, in the case of other 

 Articulata excretory organs may enter into close relationship 

 to the ingestion of food. 



The very organ that functions as a salivary gland in the 

 Hygrophilese referred to appears greatly reduced in the 



