Packard.] 314 [May 2, 
ment of Pulex canis, and remarks tliat "at the first glance the 
great similarity with the embryo of the Tipulidae is apparent," 
anil farther on, "while also the form and position of the primi- 
tive band wholly correspond to their relations in Chironomus, 
so also the composition of each segment is wholly analogous. 
. . . The number of primitive segments agrees with that of 
the Tipulidae, and the last (twelfth) segment is clearly seen to 
be due to the union of two pieces pressed together, one dorsal 
and the other ventral, between which a fine pointed prolongation 
of the yolk projects, just as is the case in the same stage of 
Chironomus (Taf. 3, fig. 32). . . . We need only state that 
the embryonal development of the flea comes nearest to that 
of the Tipulidae, that the two families belong to those insects 
which are developed out of a primitive band, which owes its 
origin to a splitting of the blastoderm" (p. 89, 90). 
In his article on the embi'yology of Pulex felis Balbiani notices 
the api)earance of rudiments of the thoracic feet, though the larva 
is batched in an apodous condition. (Comptes rendus. 1875.) 
In our brief essay on the development of Pidex canis^, we were 
also struck by the resemblance of the embryo in its different 
stages to that of Chironomus. And yet on reconsidering the 
matter, the resemblance of the embryo of the flea to that of 
certain Coleoptera (Attelabus, Telephorus, Chrysomela, etc.), 
appears to be nearly as strong, and perhaps when farther 
researches are made on the embryology of the Siphonajjtera, some 
points of resemblance may be elicited. 
The Freshly Hatched Larva. 
Fig. 1 represents a larva just ready, Nov. 9, to hatch, the egg 
having been laid Nov. 3. Just before hatching the embryo grows 
much longer, and the larva lies coiled up in the egg, with the 
head, hovvever, free from the coil. 
The young larva is very transparent, the digestive canal, heart, 
and nervous system being readily distinguishable, while the 
spiracles and tracheae wei'e not observed. In Fig. 1 the heart 
(/a) is seen to form a long slender tube, which was traced as far 
as tlie |)Osterior part of the liead, nearly reaching the back part of 
I M.-inoirs I'oabo.lv acad. sci., Salem. Mass., ]87-_'. 
