PERLlDiT?, EPHEMERIDJC. InS, 263 
Perlid^. 
Imiiof, Otiimar Emil. Beitrage zur Anatomie der Perla maxima^ 
Scopoli. Inaugural Dissertation, pp. 1-41, with two plates. Aarau: 
1881. 
A very original and apparently exhaustive essay on the anatomy of the 
nervous, digestive, and reproductive systems. 
Dictyopteryx alpina^ Piet. Notes on this species from observations in 
the Upper Engadine ; McLachlan, Ent. M. M. xvii. p. 221. 
Perla selysi^ Piet. Male described ; McLachlan, OR. Ent. Belg. xxv. 
p. cxviii. 
EpHEMERIDJ3. 
CiACCio, G. V. Sopra la notomia minuta degli occhi della Cloe diptera, 
L., Rend. Acc. Bologn. 1881, pp. 79-81. 
Eaton, A. E. An amiouncomont of now gonora of tho Ephemeridee. 
Ent. M. M. xvii. pp. 191-197 & xviii. pp. 21-27. 
Vayssiere, Albert. Etude sur I’etat parfait du Prosopistoma puncti- 
frons. Ann. Sci. Nat. (6) xi., No. 1, pp. 1-15, pi. i. 
This memoir commences with a somewhat detailed account of the 
anatomy of the nymph, the special feature being the manner in which all 
the systems have their parts or conditions “ concentrated,” owing to the 
form of the animal ; this is principally made in connection with the 
genera Gamis and TricorytJms. Then follows an account of tho changes 
in the nymph when near the period of metamorphosis, and, finally, a full 
account, both general and anatomical, of the $ sub-imago, the only con- 
dition under which the winged insect is as yet known. The relationship 
to Ccenis appears to be somewhat close. The plate illustrates the various 
stages, and figures of the nymphs of Bcetisca and Tricorythus are intro- 
duced for comparison. Extr. in Arch. sci. Nat. (3) vi. pp. 101-102; J. R. 
Micr. Soc. (2) i. p. 696 ; Biol. Centralbl. i. pp. 372-374 ; Ann. N. H. (5) 
viii. pp. 73-85, pi. x. 
Coinis maxima^ Joly. Replying to Vayssiere’s remarks on the nymph 
upon which this species is founded, Eaton states his reasons for having 
considered that it is not that of a true Ccenis ; and he is of opinion that 
it would be safer to consider it as representing something allied to Ccenis, 
perhaps a Tricorythus. or perhaps a new genus. Ent. M. M. xviii. p. 21. 
A list of 18 species collected in Belgium in July, 1880, determined by 
Eaton, is given by McLachlan in OR. Ent. Belg. xxv. p. cxxxv. Four 
species were new to the country. 
Exuviation in flight. Under this heading, C. V. Riley has a note on 
this subject from McLachlan’s observations on Oligoneuria, and his own 
on Polymitarcys alba. He is of opinion that exuviation must be com- 
menced on the surface of the water. Am. Nat. xv. p. 395. 
Two species from Sumatra belonging to the genera Rhoenanthus and 
Isonychia noticed by Albarda in Veth’s Midden-Sumatra, iv. pt. 5, p. 12. 
