346 PROCEEDINGS OF THE NATIONAL 2IUSEUM. vol 51. 



Young larva (fig. 6). — Length 0.4 mm.; width at greatest 

 diameter 0.208 mm.; shape oval, the caudal end the smaller; median 

 dorsal portion considerably elevated; color dark brown, mth here 

 and there lighter transparent areas. On the cephalic extremity 

 there is a pair of slightly curved spines averaging 0.076 mm. in length. 

 Somewhat caudad is another pair of about the same length; slightly 

 caudad of these and situated close together near the median dorsal 

 line is a pair of spines averaging 0.2 mm. in length ; caudad of these 

 and situated well out on the submarginal area is a pair of shorter 

 spines averaging 0.112 mm. in length; caudad of these again and 

 situated close together near the median dorsal line there is another 

 large pair about 0.2 mm. long; caudad of this pair is a variable number 

 of one or two pairs of minute spines, and then two pairs of well de- 

 veloped ones about 0.16 mm. long. The most caudal pair of these 

 is sHghtly the longer. Situated just cephalad of the vasiform 

 orifice is a pair of small bristles, and there is a similar spine on each side 

 of it. There is a pair of long spines, about the same length as the 

 last pair of abdominal ones, situated a spine on either side of the 

 orifice. Just within the caudal margin of the case there is a pair 

 of rather long hair-hke bristles, and on the caudo-lateral margin 

 a pair of minute ones is situated. The vasiform orifice is somewhat 

 squarish or often almost circular. It is almost completely filled by 

 the operculum which obscures the fingula. The margin of the larva 

 is bluntly serrate. 



Late larva (fig. 4). — Length 0.8 mm.; width 0.48 mm.; shape 

 elliptic; dorsum arched. On the submarginal area there is a row 

 of usually 24 spines. Of these the first and third caudal pairs and 

 the second cephalic pairs are usually considerably longer than the 

 others. On the dorsal and subdorsal areas there are 28 spines. There 

 are three long pairs on the abdomen and one long one on the thoracic 

 area. On the thorax also there is a pair of setae on the dorsal area, 

 a similar pair is situated just anterior to the vasiform orifice, and 

 another pair on the caudal margin of the case. Some specimens 

 show the first and second caudal pairs of submarginal spines long 

 instead of the first and third. The vasiform orifice (fig. 8) is situ- 

 ated on a tubercle-like structure; broadly subcordate in outUne and 

 is almost filled by the operculum. The ventral membrane of the 

 orifice is bilobed. The margin is armed mth prominent teeth, the 

 tips of which are knobbed. A space of 0.1 mm. is occupied by 12 

 or 13 teeth. 



The interspaces between these are quite acute, though the distal 

 knobbed portion is rounded; a space of 0.1 mm. is occupied by 10 

 teeth. 



Pupa case (figs. 1 and 9). — Size, 1.39 by 0.88 mm. Shape oval; 

 broadest across the abdomen; dorsum with a distinct elevated median 



