On the Internal Organisation of Cumaeea. 



(PI. LXV LXVIII). 



To show more clearly the relation of the Cumaeea to other Crustacea, 

 I propose in the following pages to give a short account of the internal organs 

 in this peculiar group. These investigations were made many years ago, chiefly 

 by the examination of fresh specimens, and only a few additions and corrections 

 have recently been supplied. In order to get a general view of the internal organs 

 in their natural situation, it is necessary to select some more pellucid forms, and 

 to examine them, while still alive, under the microscope, applying transmitted 

 light. Several of the organs may thus be at once observed, whereas other 

 organs are less distinctly traced, owing to the imperfect pellucidity of the 

 integuments. In every case a close examination of the organs cannot be accom- 

 plished without dissection. This should, if possible, be performed on fresh speci- 

 mens, immediately after they have been killed, as a dissection of specimens 

 preserved for a long time in alcohol ov other preserving fluids, always gives 

 far less satisfactory results as regards this part of the anatomy. An attempt 

 to make sections of alcoholic specimens, after applying the usual staining and 

 imbedding method, was not successful, probably owing to the difficulty with which 

 the integuments are permeated by the melted paraffin. 



l. Intestinal System. 



The intestinal tract (see PI. LXV LXVIII, fig. 1) commences with a 

 very short muscular oesophagus (PI. LXV, fig. 2, oes), which ascends almost 

 perpendicularly from the mouth to the stomachal part of the intestine (s t), and 

 is marked off from the latter inside by 2 projecting lips. The stomachal part forms 

 a considerable dilation, which extends through the part of the body covered by 

 the carapace, curving at the hindmost limit of this part abruptly downwards, and 



13 Crustacea. 



