288 Mr. Newport on the Class Myriapoda, Order Chilopoda, 



Audouin three; MacLeay and Newman four; myself, on a former occasion, 

 /■(■<■ ; and Strauss Duckheim even so many as seven. After an attentive ex- 

 amination of the head in Myriapoda, I am now constrained to believe that 

 there are not fewer than eight. 



I shall attempt to demonstrate the existence of these parts by taking for my 

 guide the appendages of the head and organs of nutrition. 



The head of the Chilopoda is formed of two moveable portions (fig. 4.), — the 

 cephalic (a) and the basilar (b, c) segments, as is well seen in Scolopendra. 

 Each of these segments is originally composed of four subsegments. In the 

 inferior genera of Chilopoda, the Geophilidce, I have been able to trace most 

 distinctly the number of segments that enter into the structure of the head of 

 this class. 



At the moment of bursting the egg-shell*, and before the rupture of the 

 proper foetal coverings, the young Geophilus longicornis (fig. 3.) of Leach has 

 the cephalic segment (a) formed of four very distinct parts (1,2,3,4), which 

 at that period are in the act of uniting to form the single cephalic segment of 

 the perfect animal (fig. 15.). The anterior of these parts (1) gives origin to 

 the antennce, while the second (2), which has no distinct appendages, is after- 

 wards found to be that in which the minute eyes of the Geophilus are situated. 

 The third (3) and fourth (4) have for appendages the maxillae and internal 

 parts of the mouth. The whole of these four segments become completely 

 united at this period, more especially the two posterior ones, which afterwards 

 are more enlarged than the anterior, within which the brain of the animal is 

 situated. The anterior always continue very minute, and do not increase in 

 size in proportion to that of any other part of the body. 



The parts which constitute the basilar segment of Scolopendra are never all 

 united in the true Geophili. In one of the higher forms of this family, Mecis- 

 tocephalus, Newp. (figs. 17, 18 and 19.), the basilar segment closely resembles 

 that of Scolopendra ; but in the other genera (figs. 10 and 1 5.) it consists of two 

 separate portions (b, c), the posterior of which (c) I have distinguished in this 

 family as the suh-hasilar segment. The original composition of the basilar 



* For the purpose of better demonstrating the analogies of the appendages of the cephalic segments, 

 as well as the existence of the segments, I have delineated the head of a young Geophilus at an ad- 

 vanced period after the bursting of the egg. 



