184 NEW YORK STATE MUSEUM 



1. Thalassomyia obscura Johannsen 

 1903 Thalassomyia -Johannsen. N. Y. State Museum bul. 68. 437 



Larva. The eggs were not found. The larva is 8 to 10 min. in 

 length when full grown, pale or yellowish green in color, its 

 head is dark 'brown and heavily chitinized. The head is some- 

 what longer than wide, the dorsal suture well marked. Two setae 

 are placed immediately in front of the transverse suture, and at 

 the apical end of the lab rum are two more. The lateral arms of the 

 ventral surface of the laibrum are rather short and stout, and some- 

 what pointed. The anterior ventral margin of the la'bruim is provided 

 with short fleshy filaments instead of. setae as is usually the case in 

 Chironomus. The antennae are small, the basal joints about 

 four times as long as wide, eaich with two terminal pieces, one of 

 which is four-jointed, the other simple. The mandible is about 

 twice as long as broad, with five blunt teeth; articulated at the 

 base is a long slender process with four terminal spines. The 

 maxillae are short protuberences, covered with pointed projec- 

 tions, with a very short palpus with its terminal papillae, and 

 two stout setae projecting ventrad. The hypopharynx is tongue- 

 like, with two long basal pieces. Its apex and its dorsal surface 

 are covered with pointed papillae; ventrally there is an open 

 arched rib. At the cephalic end of the ventral sclerite, and coales- 

 cent with it, is the labiuan, with 11 blunt marginal teeth, the 

 middle one wide and broadly truncated. On the prothoracic seg- 

 ment are the two prolegs, each with about 30 long curved spines, 

 and a number of short and very small spines on the ventral sur- 

 face. At the base is a single slender seta, on each side a little 

 dorsad of the lateral line are two more, and caudad of these and 

 below the lateral line a group of three. The eleventh segment is 

 without blood gills; the twelfth with two comparatively short 

 legs, each with a crown of 8 to 10 bifid claws ; on the dorsal sur- 

 face are two small protulberences upon each of which is a tuft of 

 five or six long setae. Between the legs and projecting caudad 

 are four short blood gills. 



Pupa. The pupa is about 4.5 mm. long, with the colors of the 

 adult. It is much shorter in comparison to its breadth than is 

 'Chironomus. The wings extend to a little beyond the pos- 

 terior margin of the second abdominal segment. Eight segments 

 are present 'besides the short anal segment. On the dorsum of 

 each segment, toward the caudal margin, is a transverse band of 

 stout black bristles. Each band is composed of five or six rows. 

 The most caudad of these rows contain the longest bristles. 

 The anal segment is composed of two small lobes, each with a 

 single apical bristle. After two to four days of pupal life it 

 transforms into the imago. (See pl.50 in N. Y. State Mus. 

 Bul. 68.) 



