8 ON THE CHILOPODA OF NORTH AMERICA. 



segment. Between them are two small plates — the lingua — (fig. 3, 1) which we think 

 are the primitive sterna, not cpisterna, (as Mr. Newport 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 

 Y js- 4 - to this is a large irregularly four-sided one, forming a portion of the palpus, 

 (fig. 4, a ;) this is one of the primitive sterna of the first basilar subseg- 

 ment ; still within this is an elongated plate, (e,) the coxa of the palpus. 

 With these two last the femur (b) of the palpus is articulated at its 

 proximate end, while to its distal end is fitted the tibia (x) and to it the 

 tarsus, (m.) The sterna and appendages of the second and third are 

 very much coalesced and difficult to distinguish clearly ; but we think that the dental 

 lamina are probably the appendages of the second basilar subsegment, the anterior 

 portion of the labium, which we have frequently seen separated by a suture, being 

 composed of the episterna and primitive sterna of the same subsegment. The mandibles 

 are probably the appendages of the third basilar subsegment, the posterior portion of 

 the labium being composed of the sterna of the same subsegment. Two plates, which 

 are bent round the sides of the posterior portion of the labium, we take to be the epi- 

 sterna. The sternal portions of the fourth basilar subsegment are similar to those of the 

 segments of the body. Among the Lithobiidae the structure of the under portion of 

 the head is almost identical with that described above. 



Among the Geophilidse the parts of the mouth are so consolidated and confused 

 that it is impossible to recognize in the adult the original plan of construction and 

 development. On examining the under surface of the head of a Mecistocephalus, we 

 will find the labium very large, as are also the mandibles, while the maxillse are 

 apparently wanting, but the maxillary palpi are recognizable. Among the Cerma- 

 tiidae the labium is moderate, cleft in the middle, the two lateral halves being move- 

 able on one another, so as to form as it were an additional joint to the mandibles ; 

 otherwise enormously developed, especially as to length. The palpi are very long. 

 The maxillse and maxillary palpi well developed. 



Fam. I. CERMATIID^E, Leach. 



Scuta dorsalia 8. Segmenta 16. Sterna 15. Scutorura stomata mediana. Pedes antennEeque rmilti- 



artieulatse. 



In the Cermatiidae the head is large, more or less truncate anteriorly, having its 

 surface rough and uneven. The eyes are compound and very prominent. The palpi 

 much elongate and spinous. The antennae very long and composed of a multitude of 

 joints. The mandibles are elongate and distant. The scuta (eight in number) are 

 rounded and deeply emarginate posteriorly, where they are furnished with a longi- 

 tudinal, slit-like orifice or stoma. Their surface is more or less roughened with minute 



