APHANIPTERA, 27 
lip has four setaceous hairs upon its under surface. On the dorsal 
surface of the head we must be careful to note the curious structure 
known as the “pointe frontale,” so well described in Kunckel’s 
paper. It is present in the young larvz, and may be seen prior to 
its exit from the egg. It is a yellowish-brown, horny plate, and 
seems to vary in shape in the different species of fleas. This appears 
to have been first noticed by De Geer.* 
This little corneous plate is placed in a slight depression of 
the head, and ends in front in a sharp point: the figure will, 
however, explain best its general shape and appearance in the 
species of Pulex; namely, P. felis (vide Fig. 1). It must be 
noticed that this structure is only found in the young larve. It is 
possibly an organ used to rupture the egg membranes, and thus 
release the larva. It is no doubt the homologue of the “dorsal 
plate” found in other insects, so fully described by Kowalevsky,t 
and again by Dohrn,{ who says it is formed from a thickening of 
the serous membrane which covers the dorsal surface; this differs, 
however, from our “ pointe frontale” by becoming formed into a canal 
and then intoatube. This frontal plate, seen in embryo fleas and 
in Pentatomes, in the Phryganide, and as -the so-called “ dorsal 
plate” of Hydrophilus, etc., is also, according to Kunckel, homo- 
logous to a piece which, if it is developed, exists in the front of the 
larve of Crustacea, the Zoza of Cancer menas and Pagures and 
Porcellanes, of young lobsters, etc. 
M. Balbiani also notices a curious point in the frontal region of 
young Phalangide,§ which he regards as the analogue of the 
appendages found on the dorsal surface in other Arthropods. We 
may also note the antennz situated on the dorsal surface of the 
head. They are composed of three joints: the first being rounded, 
and bearing a few protuberances ; the second is cylindrical, and ends 
in tentacular-like processes ; from this proceeds the third joint, 
which is small and pointed. 
The Alimentary Canal.—This is easily seen in living larve, owing 
to their transparency. Two small elongated salivary glands open 
into the pharynx, which is followed by a short and swollen esophagus, 
which gradually narrows as it passes into the chylific ventricle; this 
part of the digestive track is large and elongated, its posterior end is 
* De Geer, ‘* Mémoires pour servir 4 I’Histoire des Insectes,” 1778. 
t+ ‘* Embryologische Studien an Wiirmern u. Arthropoden.” Mém. Ac. Imp., 
Petersbourg, S. vii., vol. xvi., 1871. 
ee, Notizen zur Kenntniss d. Insectenentwickelung.” Zeitschrift f. wiss. Zool., 
§ eee sur le Développement des Phalangides.” Ann. Scien. Nat., vol. 
xvi., 1872. 
