On a new Trichocera from Siberia. 431 
that have been described—Paludina (3), Bithinia (9), Tan- 
ganyikia and Melania (8)—the brood-pouch opens directly to 
the exterior by a terminal (vaginal) pore. On the other 
hand, in Cyclostoma elegans (4) the vaginal aperture is 
apparently not at the extremity of the brood-pouch, as the 
latter “est un organe tubulaire terminé inférieurement en 
cul-de-sac et présentant latéralement une large fente, la vulve.” 
WORKS REFERRED TO. 
(1) Bernarp, F. Bull. Sci. France et Belgique, xxii. (1890). 
(2) Boycorr, A. KE. Journal of Conchology, xvi. no. 2 (1919). 
(3) Bronn, H. Klassen und Ordnungen des Thierreichs. 
(4) GaRnavxT, P. Actes Soc. Linn. Bordeaux, xli. (1887). 
(5) Henxrne, H. Berichte Naturf. Ges. Freiburg, vii. (1894). 
(6) Leumann, R. Schnecken und Muscheln.... Stettins, (Cassel, 
1878). 
_ (7) Meyer, H., and Mosrus, K. Fauna der Kieler Bucht, ii. (1872). 
(8) Moorr, J. E.S. Quart. Journ. Micr. Sci. xli. (1898). 
(9) Moqurn Tanpon, A. Moll. de France (Paris, 1855). 
(10) Quick, H. EK. Journal vf Conchology, xvi. no. 3 (1920). 
(11) Ranpuxs, W. B. Quart. Journ. Micr. Sci. xlviii. (1905), 
(12) Srwrorn, H. Zool. Anz. Jahrg. iv. no. 94. 
(13) Smiru, E. A. Journal of Conchology, vi. (1889), 
(14) Woopwarp, B. B. Ann. & Mag. Nat. Hist. ix. (1892). 
EXPLANATION OF PLATE XV. 
Fig. 1. Paludestrina jenkinsi. Transverse section of mouth, showing 
cuticle (c.) and mandibles (m.), [Cam. 4 oc. x6 obj. Reich.] 
Fig. 2. Ditto. Diagrammatic transverse section through cesophagus. 
[4 oc. x6 obj. Reich. ] 
Fig. 3. Ditto. Crystalline style. [Cam. 4 oc. 3 obj. Reich.] 
Fig. 4. Ditto. Section through stomach-wall. c.=cuticle. [Cam. 40c. 
x 6 obj. Reich. ] 
Fig. 5, Ditto. Section through gill-filaments and supporting lamella. 
[Cam. comp. 6 oc. x 6 obj. Reich. ] 
Fig. 6. Ditto. Heart: section through auricle (a.) and ventricle (v.). 
[Cam. 4 oc. x 6 obj. Reich. | 
Fig. 7. Ditto. Sections through (A) junction of oviduct with yolk-bearing 
ovarian tubule; (B) ovarian tubule, showing odcytes and yolk 
in epithelium. y.=yolk; od.=oviduct. 
Fig. 8. Ditto. Section through junction (av.) between spermatheca and 
vagina, and connection of albumen-gland (ag.) and vagina (v.) 
with brood-pouch (dp.). od.=oviduct. [Cam. 4 oc. x6 obj. | 
LVIUI.—A new Trichocera from Siberia (Diptera Polyneura). 
By F. W. Epwarps. 
(Published by permission of the Trustees of the British Museum.) 
AMONG a collection of mosquitoes recently sent me for deter- 
mination by Prof. Yngve Sjéstedt, of Stockholm, was a single 
male specimen of a Trichocera which, though differing little 
