118 STALK-EYED CRUSTACEA. 
are hardly distinguishable. It follows that unless the adult male be known, a 
species cannot be referred to its proper genus in Bate’s system. That author 
was most arbitrary in the disposal of his own species, for three of those 
which he placed in Pentacheles, viz. obscurus, levis, and gracilis, were known 
to him only through the female. Keeping the above-mentioned facts in 
view, I have deemed it advisable to unite Pentacheles and Polycheles, provision- 
ally at least. For similar reasons I have not recognized Bate’s genus S/erco- 
mastis, which was instituted in 1888,* for the reception of two species which 
lack epipods on the thoracic appendages, but in all other respects agree with 
Pentacheles. An examination of a large number of species discloses a gradual 
transition in the development of the epipods, from large well developed or- 
gans through small, delicate and thin ones, to merest rudiments in the shape 
of small expansions at the base of the stem of the gill. 
Furthermore, a nomenclatural difficulty confronts him who treats of 
this family, arising from our imperfect knowledge of the structure of the 
eye in P. typhlops Heller, the type of the genus Polycheles. In Polycheles of 
this report (= Polycheles + Pentacheles + Stereomastis of Bate) the ophthalmic 
lobes are lodged in a deep notch or sinus of the anterior margin of the cara- 
pace and send off from their anterior portion a long cylindrical process 
beneath the anterior lateral angle of the carapace. In Willemoesia Grote 
(type, W. leptodactyla W.-Suhm) the ophthalmic lobe is situate in the metope 
and is not lodged in a sinus of the carapace, nor does it send off a process 
beneath the anterior lateral angle of the carapace. Of Polycheles typhlops 
Heller says:f “ Die Augen fehlen fast ganz, nur an der Basis der oberen 
Antennen gewahrt man an der Stelle, wo sich der Stirnrand nach unten 
umbiegt, zwei schwarze rundliche Flecken als Rudimente derselben.” This 
description applies more nearly to the eye of Wi/lemoesia than to that of Poly- 
cheles of Bate and more recent authors.t On the other hand, the notch in 
the anterior margin of the carapace, although rather shallow, and the gen- 
eral character of the carapace as shown in Heller’s figure, indicate a species 
congeneric with those which have since been placed in Polycheles. Should a 
re-examination of the type of Polycheles typhlops reveal an eye constructed as 
* Rep. Challenger Macrura, p. 154, 1888. 
+ Sitzungsber. Kais. Akad. Wissensch. Wien, XLV., Abth. I., 390, 1862. 
£ In Willemoesia the posterior thoracic feet are chelate in both sexes, while in the type specimen of 
P. typhlops (a male) these appendages are simple. But much stress cannot be laid upon this difference, since 
Heller’s unique specimen of P. ¢yphlops was only two inches in length. Norman’s description of P. ¢yphlops 
(Ann. Mag. Nat. Hist., 5th Ser., IV., 176, 1879) has no bearing on the point here under consideration, since 
it is very doubtful whether the specimens described by him are the same as Heller’s species. 
