THE GENUS CALOSOMA. 49 



being rounded posteriorly and bearing a pair of caudal appendages. I Each segment 

 except the last bears six hairs, one on each lateral margin and two on each side of the 

 dorsal line at the posterior margin. The last abdominal segment bears a pair of hairs 

 on each lateral margin, but none on the dorsum. The caudal appendages are entire, 

 although probably jointed at the base, and bear numerous hairs. The spiracles are 

 situated just below the dorsal plates. The ventral portion of the body is of a yellowish 

 white except the portions which are strengthened by chitinous plates. These are 

 of the same color as the dorsal part of the body. Legs well-developed, provided with 

 stout spines which are especially prominentat the joints, the tarsi bearing two claws. 

 The last body segment bears on the posterior ventral portion an appendage which 

 serves as a proleg and aids in locomotion. The larva remains in this stage about four 

 days. Molting is accomplished by a splitting of the thoracic plates along the dorsal 

 line; the head, mouth parts and legs are then withdrawn and the exuviae forced 

 back over the posterior end of the body. The newly molted larva is of a pale straw 

 color. 



Second stage. — Length, 15 mm.; width, 3 mm. Form somewhat stouter than in the 

 preceding stage. Head relatively smaller, flattened, as wide as long; eyes less promi- 

 nent. Clypeus deeply emarginate in front and feebly incised at the middle. Anten- 

 nae and mouth parts relatively the same as in the last stage; the body, however, is 

 of a somewhat paler brown color. All the body segments except the last are trun- 

 cate behind, and bear a well-defined dorsal line. The first thoracic segment is broad- 

 est posteriorly and gradually narrows toward the head, but is not quite as wide as the 

 two succeeding segments. The hairs are arranged the same as in the first stage, 

 except that two pairs of hairs arise on the lateral edges of each segment up to the last, 

 which bears only one pair. The caudal appendages are entire but not quite as promi- 

 nent as in the previous stage, and the legs are a little more slender. The time spent 

 in this stage varies from four to eleven days. 



Third stage. — After molting the larva measures 22 mm. in length and 4 mm. in 

 width, and is of a light mahogany-brown color, which soon changes to a dark seal 

 brown. The mandibles are stout, and bear a prominent carina. The clypeus is 

 deeply bilobed in front, the hinder border separated from the epicranium by a some- 

 what indistinct suture. Prothorax narrowed in front and much wider behind. Caudal 

 appendages each provided with a blunt spine, which is thickened at the base and 

 arises from the dorsal surface. When full grown the larva is very stout, and measures 

 32 mm. in length, and 6 mm. in width. A detailed description of the full-grown 

 larva follows: 



The head is of medium size, slightly flattened and of the same color as the body. 

 Clypeus somewhat shield shaped. A faint line separates the clypeus from the epi- 

 cranium and reaches to the base of the mandibles, but does not divide the raised 

 portions which bear the antennae. Front edge of clypeus strongly bilobed, each 

 anterior angle bearing a prominent spine ; top of the clypeus slightly hollowed toward 

 the dorsal line. The spines are the same in number and arrangement as in the 

 previous stages. Eyes near base of antennae, not prominent. The antennae are 

 setaceous, short, four-jointed, and arise from an elevation at the base of the mandibles. 

 First joint short, cylindrical and naked; second joint nearly twice as long, slightly 

 clavate and bearing a short hair near the middle of the outer margin; third joint a 

 little shorter than the second, somewhat clavate and having one anterior angle slightly 

 produced, and bearing three spines, which arise near the outer angles; last joint as 

 long as the first, nearly cylindrical and bearing three spines at the apex. Mandibles 

 large, stout at base, with a prominent dorsal carina. A strong, simple, blunt tooth 

 arises near the base. The mandible gradually tapers from the outermost insertion 

 of this tooth to a somewhat chisel-shaped point. The maxillae are small, ferruginous 

 in color, and are densely covered with hairs and spines. They bear four-jointed, 

 naked palpi, which are nearly as long as the antennae. The three inner segments of 

 the maxillary palpus are short, stout, truncate, and of nearly equal length; the term- 

 inal joint is slightly longer than the two preceding joints, oblong ovate in form and 

 truncate at the tip. The galea or inner lobe is naked, two-jointed and as long as the 

 three basal joints of the palpus. Lacinia prominent and bearing a spine at its apex. 

 Labium small, somewhat halberd shaped, with numerous spines arranged in an oval 

 row on the inner side. Palpi two-jointed; outer joint the longer and truncate at tip. 



The dorsal thoracic plates are large, and nearly cover the lateral thoracic walls, 

 while the dorsal abdominal plates, with the exception of the last, are smaller, and 

 allow the lateral walls of the abdomen to protrude. Dorsal line not prominent. Each 

 abdominal plate except the last bears, near the posterior margin, a very feeble trans- 

 verse carina. Spines are arranged as in the preceding stage. The last segment is 

 relatively small, nearly truncate behind; the caudal appendages of moderate length, 

 and each bears on the upper surface a large, blunt, hornlike protuberance, which is 



54880°— Bull. 417—17 4 



