with Observations on the General Arrangement of the Articulata. 297 



in Lithobius as in Scohpendra, excepting only that the femoral poftion of the 

 palpus is more elongated. In Cermatia also the same analogies are preserved ; 

 the coxa exists on the front of the episternum, but receives the whole articu- 

 lation of the femur. This joint, like the chief portion of the mandibles, is 

 armed with its spines, as also is the tibia. A considerable elongation has also 

 taken place in these parts, and the tarsus is formed of two joints. 



These are the analogies of the most developed and important parts of the 

 basilar region of the head, and the like exist in those of the cephalic region ; 

 but it is only by remembering, and by taking for our guide the important 

 fact that the coxal joint of the limb constantly exists, and is never entirely 

 lost, although often in part united with the episternum, with which it always 

 articulates, that we are enabled with certainty to trace these analogies. 



The cephalic region of the head, like the basilar, gives origin to two pairs 

 of moveable organs of nutrition. These are the appendages of the third and 

 fourth segments. The posterior pair (fig. /.) are connected transversely at 

 their base with a pair of soft appendages (c, c), that are situated between them, 

 and which, as I have already stated, I regard as the proper lingua, as they form 

 the floor of the entrance to the pharynx. These appendages are the remains 

 of the episternal plates, while the coxae are represented by the large basal 

 joint of the palpus {f), the external maxillary palpus of Insects. The remain- 

 ing pair of appendages are the most anterior and internal of the moveable 

 organs of the mouth, and are the true maxillse (fig. 8.*). They are the appen- 

 dages of the third cephalic segment. They are formed each of three corneous 

 triangular plates {g, h, i) that articulate freely with each other, and represent 

 the femur, the tibia and the tarsus. They perform the office of comminuting 

 the food before it is passed on to the pharynx. 



Besides these moveable parts there are others that are articulated together, 

 and are united at their extremities in the middle line, and form an arch in 

 front of the entrance to the mouth anterior to the moveable organs. These 

 seem to constitute the anterior lip (fig. 8.), and belong to the second segment. 

 They are composed each of two subquadrate horny plates {h, h), articulated to- 

 gether, and united in the middle line by a sharp triangular tooth (<). Although 

 it is difficult to trace with certainty the analogies of these parts, they seem to 

 represent the appendages of the second segment ; and there is a very precise 



