CRUSTACEA. 29 



forward part of the body near the mouth, and not to 

 any pair immediately below. 



Prepare a fresh specimen by cutting through the 

 sternal part of the rephalothorax, between the first and 

 second pair of maxillae. Figs. 9, 9 A, cd, show where the 

 separation should be made. Fig. 9 is a view of the cepha- 

 lothorax from below. The thoracic appendages have 

 been removed, so that irregular cavities (Xos. 1-9) are 

 seen where the appendages were articulated to the 

 body, at- 2 (Xo. 2) is the place of attachment of the 

 second pair of maxillae, ad i—ad 3 (Xos. 1.3. 4) of 

 the maxillipeds, and ae i—ae 5 (Xos. 5, 6, 7, 8, 9) 

 of the walkingdegs. On the right side the first pair 

 of maxillae are shown, fig. 9 .1 shows even more plainly 

 the course of the knife along ed and between the cavi- 

 ties representing the first pair of maxillae (ac 1) and the 

 second pair of maxillae (ac 2). When this separation 

 has been made, the carapace may be gently raised and 

 torn off; the appendages belonging to the thorax will 

 then remain attached to the under side of that part, and 

 those belonging to the shield itself will come off with it. 



As there are different views with regard to the limits of 

 the thorax, it is necessary to state that the space between 

 the first and second pair of maxillae is membranous entirely 

 across the sternal region. The continuous calcification of 

 the sternal plates which distinguishes the thorax includes 

 the sternum of the second pair of maxillae, and the little 

 plate (Figs. 9. 9 ./, sue 1) at the posterior border of the 

 mouth is separated by a pliable hinge from the sternum 

 of the second pair of maxilla'. This also affords attach- 

 ment to the more or less calcified bases of the leaf-like 

 appendages (Fig. 9 . /. mi, //// 1) of the posterior lip or 

 labium (//;///) of the mouth. 



