ZOOLOGY OF THE FAR EAST. 
convoluted ejaculatory duct gives rise to an obliquely upwardly and backwardly 
directed tube, which is provided with a thick wall and probably represents the pros- 
tate. The features of the male end-organs seem to differ remarkably from those of 
any other species of the genus. 
Female Genital Organs. — The ovaries are dorsal in position. The end-organs 
consist of parts closely similar to those of the preceding species. The two uteri 
unite into a single median uterine duct before joining the median egg-canal. The 
egg-canal proceeds backward to enter the medial part of the accessory vesicle, which 
seems to present features similar to those of the same organ of the preceding species. 
Anteriorly the egg-canal bends abruptly downward and backward, and then takes a 
posteriorly directed course, in which it is abundantly supplied with shell glands. Un- 
fortunately I have not been able to observe the further course of the egg-canal and 
the position of the female aperture. 
Remarks. — The present species seems to be nearly allied to Sh. annandalei, so 
much so that it may well be referred to the same genus. But it stands distinctly at 
variance from that species in the arrangement of eye-spots as well as in some points 
of the genital end-organs, as may be seen from the above description. 
In conclusion, a few words with regard to the Polyclads hitherto known from 
Siam. Since the appearance of Collingwood's memoir our knowledge concerning 
the Polyclad-fauna of the Malay Peninsula and vicinity has been augmented by 
lyang^, Laidlaw^, Bock*, and some others. From among the species described by 
these authors, the following eight forms have been known to occur in Siam : — 
(1) Meixneria furva Bock. 
(2) Stylochus orientalis Bock. 
(3) St. orientalis var. splendida Bock, 
(4) St. hyalinus Bock. 
(5) Notoplana evansi Laidlaw . 
(6) N. mortenseni Bock. 
(7) Copidoplana paradoxa Bock. 
(8) Pseudoceros litoralis Bock. 
The following is a key to all these species and the two described in this paper : — 
I. Without sucking disc on ventral surface . . . . . . Suborder Acotylea. 
A. Marginal eye-spots present . . . . . . • . Section Craspedommata. 
a^ Tentacles present. Without accessory vesicle to vagina, 
a*. Vagina very long . . . . . • • • Genus M eixneria. 
1 Collingwood, V., 1876. " On thirty-one species of Marine Planarians collected partly by the late Dr. Kelaart 
F.L.S., at Trincomalae, and partly by Dr. Collingwood, P.L.S., in the Eastern Seas." Transact. Linn. Soc. London, 
2 ser. , Zool., Vol. I. 
2 Lang, A., 1884. " Die Polycladen." Fauna u. Flora des Golf es von Neapel. XI. Monographic. 
Laidlaw, F. F., 1903. " On a Collection of Turbellaria Polycladida from the Straits of Malacca" (Skeat. Exped. , 
1899 — 1900). Proc. Zool. Soc. London. Vol. I. 
■* Bock, sixteen, 1913. " Studien iiber Polycladen." Zool. Bid. f. Uppsala. Bd. 2. 
