1^13 Carpenter. — The h-ish Species of Petrobius, 233 
3. Terminal repjion of right m mdiblc of younger fcniale (penulti- 
mate instar) ; a, apex ; w, ntolar area. The new cuticle of 
this region can be seen within ; note the feebly toothed apex. 
X 56. 
4. Hypopharynx {hy) front aspect, with the left maxillula {Ml.) 
slightly displaced laterally, but retaining its membranous 
connection with the base of the hypopharynx. /, lacinia, ^, 
galea, p, palp of ntaxillula ; />r, peduncle of hypopharynx. 
X 28. 
5. Fifth abdominal segment of male, ventral aspect. 5, sternum, 
sc, sub-coxa, st, stylet ; vc, exsertile vesicles. x 28. 
6. Right maxilla of female, hinder aspect, c, cardo ; 5/, stipes ; 
/, lacinia ; g, galea ; p, palp. x 28. 
6a. Head of lacinia showing apex (a), " brush " (6), and acute 
processes (c and d). x 90. 
Ob. Head of lacinia from a specimen in the penultimate stage, 
showing apex {a), " brush '" (&), and acute processes (c and d) 
greatly worn, and new cuticle of head formed within, x 9^. 
7. Labial palp of female. x 28. 
A, sensory spines from its apex. x 180. 
8. Eighth abdominal segment of male, ventral aspect, s, sternum ; 
sCy sub-coxa ; 5/, stylet. x 28. 
9. Ninth abdominal segment of male, ventral aspect. sc, sub- 
coxa ; st, stylet ; g, gonapophysis ; p, penis. The right sub- 
coxa is partly broken away to expose the gonapophyes. 
X 28. 
Explanation of Plate 3. 
Structural details of Petrohiiis maritimus. 
Fig. I, Diagram showing shapes and positions of compound e^^es {e), 
lateral ocelli (o), and median ocellus {mo). x 28. 
II. Right mandible of female, hinder aspect, c, condyle ; a, apex ; 
m, molar area. x 28. 
III. Terminal region of the same mandible, a, apex ; m, molar area. 
X 56. 
IV. Left maxillula, hinder aspect. /, lacinia ; g, galea ; p, palp. 
X 56. 
V. Fifth abdominal segment of male, ventral aspect. s, sternum ; 
sc, sub-coxa ; 5/, stylet ; ve, exsertile vesicles. x 28. 
VI. Left maxilla of female, front aspect, c, cardo ; st, stipes ; /, 
lacinia ; g, galea ; p, palp. x 28. 
VII. Labial palp of female. x 28. 
A, sensory spines from its apex. x 180. 
VIII. Eighth abdominal segment of male, ventral aspect, s, sternum ; 
sc, sub-coxa ; 5/, stylet. x 28. 
IX. Ninth abdominal segment of male, ventral aspect, sc, sub- 
coxa ; st, stylet ; g, gonapophysis ; p. penis. The right sub- 
coxa is partly broken away to expose the gonapophyses. x 28, 
Royal College of Science, Dublin. 
