320 Dr Coldstream ow the Structure and 



A pair of legs is attached to each of the seven segments of the 

 body. They are articulated just under the sloping edge of the 

 dorsal crust, and, being partly folded beneath the abdomen, a 

 small portion only of each is seen to project laterally when the ani- 

 mal is in motion. Their general arrangement is represented in 

 fig. 2. (PI. VI.), and the details of their structure in figs. 3, 4, and 5. 

 They are composed of from four to six articulations. The long- 

 est are the first and fifth pairs. Those of the first are repre- 

 sented in fig. 3 ; the whole length is about igo^^s of an inch, 

 and there are four articulations. The first articulation is the 

 longest. The second bears upon its inferior surface a row of 

 tubercles. The claw is strong and sharp. The legs of the se- 

 cond segment are shorter and thicker than those of the first, and 

 have the tubercles less fully developed. Those of the third and 

 fourth are similar to these. (Fig. 4. PI. VI.) That of the 

 fifth (fig. 5.) is more slender, composed of six articulations, of 

 which the two first are of equal length. The sixth and seventh 

 pairs of legs are similar to it, but somewhat smaller. The ter- 

 minating claw is, in all, single, and somewhat hooked. All the 

 legs bear short hairs scattered over their surface. 



I have no details to offer regarding the muscular or the ner- 

 vous systems. The extreme minuteness of the parts renders it 

 almost impossible to examine them satisfactorily, even with the aid 

 of high magnifying powers. It is not improbable that the ner- 

 vous system bears some analogy to that of the Cymothoa, which, 

 being a much larger animal, has been successfully anatomized 

 by Messrs Audouin and Millne Edwards. (Annales des Sci- 

 ences Naturelles, tom. xiv. p. 77.) From their researches it ap- 

 pears, that the Cymothoa has one large ganglion in each seg- 

 ment, which sends off two nervous filaments on either side to 

 supply the viscera and legs ; and two filaments of communica- 

 tion, anterior and posterior, connecting it with the ganglia of the 

 other segments. These last lie close together, so as almost to 

 form one cord. 



The only organs of sensation discoverable in the Limnoria, 

 are the four feelers, two eyes, and the compound styles which 

 project from the caudal segment. The feelers, or antennae, are 

 placed on the most prominent part of the head, a pair on either 

 side, one of each above the other. The superior ones arise very 



