THE MTRIAPODA OF NORTH AMERICA. 



143 



suture we will find posteriorly a larger plate (Fig. 3, d), which articulates on its inner side 

 with another obliquely transverse plate (b), which also is conjoined on its inner side by 

 another (c), and that too by another, and finally in the cen- Fig . 3 . 



tre there is a small tooth, as it were. These plates are re- 

 spectively the coxa, femur, tibia, tarsus, and the rudimentary 

 m etatarsse (the central tooth) of the atrophied and misplaced 

 appendages of the second cephalic subsegment. The tibia 

 and tarsus are generally anchylosed together, but I have 

 seen them separate. Conjoined and posterior to the coxa of 

 the second cephalic subsegment we will find a large plate (a) 

 articulating with the cephalic scutum by suture ; this I take 

 to be the primitive sternum and episternum of the third 

 cephalic subsegment atrophied and fused together ; to it the 

 true maxillae are articulated. These consist each of, first an 

 elongated crooked plate (the coxa) articulating with two 

 plates, the exterior of which (the femur) is armed with a tubercle, as in the mandibles, 

 posterior legs, &c. ; the inner plate is the tibia ; these two plates articulate at their distal 

 end with a third, the tarsus and metatarsus coalescent, but with the line of their junction 

 very apparent. The maxilla? I believe to be the appendages of the third cephalic subseg- 

 ment. Just anterior to the primitive sternum of the first, and posterior to that of the 

 third, are often found some small plates which I believe to be epimeral. But the largest 

 of the latter is probably the episternum of the fourth cephalic subsegment, which is 

 scarcely to be found elsewhere. Proceeding still posteriorly we come to Fig. *• 



the maxillary palpi (Fig. 4), which are possessed each of a distinct femur 

 (/'), tibia (x), and tarso-metatarsal joint (m). They are the appendages 

 of the fourth cephalic subsegment. Between them are two small plates, 

 the lingua (Fig. 4, Z), which I think are the primitive sterna, not episterna (as Mr. New- 

 port believed), of the fourth cephalic subsegment. Posterior to the sterno-episternal plate 

 of the third subsegment is a subtriangular plate, one of the episterna of the first basilar 

 subsegment ; interior to this is a large irregularly four-sided one, forming 

 a portion of the palpus (Fig. 5, a) ; this is one of the primitive sterna of 

 the first basilar subsegment ; still within this is an elongated plate (e), 

 the coxa of the palpus. With these two last the femur (6) of the palpus 

 is articulated at its proximate end, while to its distal end is fitted the 

 tibia (x), and to it the tarsus (/??). The sterna and appendages of the 

 second and third are very much coalesced and difficult to distinguish clearly ; but I think 

 that the dental lamina are probably the appendages of the second basilar subsegment, the 



