Functio7is of' the Lhinnoria Terehra/ns. 323 



fifth segment, are distinctly seen four tubiform tapering organs, 

 closed at their distal extremities (see Fig. 12, hh.) These vary 

 in length in different individuals, but, generally, there are ttvo 

 longer and two shorter. They seem to be filled with a tena- 

 cious transparent substance, intermixed with very minute irre- 

 gularly-shaped particles ; sometimes they are annulated. Or- 

 gans nearly similar are found in the common slater (Claportus 

 asc'llus), but in it, instead of being straight, they are waved. 

 They appear to bear some analogy, in situation and structure, 

 to what have been termed salivary or hepatic vessels in some 

 coleopterous insects, particularly in Liccus angustatus and Coo- 

 cinella argus. (Dufour, Recherches anatomiques sur plu- 

 sieurs Insectes Coleopteres. Ann. des Sc. Nat. tome iv. 103.) 



The oesophagus seems to bend upwards after leaving the 

 head, and to terminate in the stomach, about the middle of the 

 first segment of the body. There the alimentary canal is first 

 distinctly visible through the dorsal crust. The transverse 

 diameter of the stomach is equal to about Jth of the breadth of 

 the body ; it is generally seen filled with yellowish- white matter. 

 From the middle of the first segment, the stomach descends 

 obliquely towards the ventral aspect, till it reaches the sixth 

 segment, where the canal is suddenly recurved upon itself up- 

 wards, and becomes contracted, marking, probably, the com- 

 mencement of the intestine, which is seen again expanded about 

 the middle of the fifth segment (see Fig. 1, where the dark 

 'markings, in the dorsal aspect represent the alimentary canal, so 

 far as it is generally visible through the crust ; and Fig. 12, 

 which is intended as a diagram of the whole alimentary canal, 

 the two pairs of jaws having been removed,) The intestine is 

 quite straight, and terminates beneath the posterior margin of 

 the last segment. It is generally stuffed with yellowish pulpy 

 matter. 



The organs of circulation have hitherto eluded my search. 

 Although aided by high magnifying powers, I have never seen 

 the globules of the blood in the Limnoria carried along in the 

 torrent of the circulation, as may be very satisfactorily seen in 

 some other minute Crustacea ; nor can I detect any dorsal ves- 

 sel. But the respiratory organs are less obscure. They con- 

 «st of six pairs of scale-hke bodies, pendant from the anterior 



