30 THE BUTTERFI.IKS OF NEW ENGLAND. 



the abdomen to be nearly straight in a h)ngitudinal dire -^ ion, while the 

 upper surface is strongly curbed ; in the Hesperidae, however, this is not 

 the case. The tenth segment is peculiarly modified to form the cremaster 

 or anal button (87:1), a more or less tetraquetral, tapering, curving, 

 bluntly docked prominence, its convexity upward, homologous with the 

 anal plate of the caterpillar, its apex and sometimes its inferior surface 

 furnished with a very large number of long and slender, cylindrical, cor- 

 neous hooks, strongly crooked and usually thickened at the distal extremity, 

 by means of which the chrysalis is securely fastened to the silk the larva 

 has spun. In the Lycaeninae the extremity of the abdomen is so curved 

 over as to l)ring the cremaster upon the under surface and it simply forms 

 a slightly tumid mass, bearing the booklets on its outer and posterior 

 ed"-es. At the inferior base of the cremaster, upon the ventral surface of 

 the ninth abdominal segment, is the closed anal orifice, its sides broadly but 

 slightly tumid and these again often bounded by curving ridges ending in 

 an anterior tubercle, homologous, as Riley has shown, with the analprolegs 

 of the caterpillar, the whole part being often so greatly developed, espec- 

 ially in the Nymphalidae, as to crowd still further the ventral surfaces of the 

 segments just anterior to it. The s})iracles are transverse slits bounded by 

 semilunar lips and occur on the second to the eighth abdominal segments, 

 those on the second and third being partially concealed by the upper portion 

 of the wings. Occasionally (e. g., Basilarchia) a single segment, or more 

 frequently (e. g., Pieris, Lacrtias, etc.) two or three consecutive segments 

 on the anterior part of the abdomen have median or lateral prominences ; 

 but the most ordinary armature consists of series of tubercles, warts or 

 simi)le s})ines arranged in longitudinal rows, in each of which there is one 

 appendage to each, or nearly every segment, except the last two : occasion- 

 ally there is a lateral continuous or nearly continuous ridge of considera- 

 ble prominence, and there is also frequently a slight median ridge ; trans- 

 verse ridges of any considerable prominence seldom occur and are then 

 usually confined, at least the conspicuous ones, to a single segment, and 

 es})ecially to the fourth abdominal segment. 



Internal structure (PI. 62, fig. 5). 



For tbc sake of readier comparison, we will follow here the same order 

 iiursued in our account of the internal organs of the caterpillar ; but so 

 little is known of the variations in the internal structure of chrysalids of 

 l)uttei-flies, that our account nuist be very imperfect. 



Muscular systen\. The tborax is almost entirely given up to muscular 

 bundh's, tbe [)rincii)le portion of which, for the movement of the future 

 wino's, is di\ isible into two sets. One of these sets is restricted to the 

 lower part of the sides of the thortix, and its fibres are directed from the 

 base of the wings toward tlie middle of the lower surface, those of the oi)]>o- 



