1870.] REV. 0. P. CAMBRIDGE ON THE GENUS IDIOPS. 101 
SEMIPLOTUS MODESTUS, sp. nov. 
ene 19.74/20 P15:)*V, 9. Ae /6.- CF 1927 LT. 52-34. 
L. tr. 73/73. 
Length of head 2, of caudal 2, height of body nearly 4 of the 
total length. 
Eyes. Diameter + of length of head, 1 diameter from end of snout, 
14 diameter apart. 
Snout broad, obtuse, with several open pores on either side. 
Mouth transverse, inferior. The posterior extremity of the maxilla 
extends to beneath the middle of the orbit. No horny substance on 
the jaws. Lower jaw not covered by lip. A knob at the symphysis. 
Slight motion between the maxillary and intermaxillary bones. No 
barbels. 
Teeth pharyngeal, 4, 3, 2/2, 3, 4. 
Colours. Silvery, darkest in the upper half of the body. Ven- 
trals and anal tipped with orange. 
Hab. Hill-ranges of Akyab, whence Col. Stevenson procured for 
me two specimens, of 44 and 53 inches respectively in length. 
Remarks.—This species appears intermediate between the genera 
Semiplotus and Cyprinion; for it nearly agrees with the former in 
the slight motion of the upper jaw, absence of barbels, &c., whilst 
it likewise resembles the latter in having a serrated dorsal spine, 
although it has no horny edge to the lips or barbels. However, 
those two genera, with this intermediate species, appear to pass so 
naturally one into the other that I would suggest they should only 
be regarded as subgenera. 
4. Monograph of the Genus Jdiops, including Descriptions 
of several Species new to Science. By the Rev. O. P. 
CAMBRIDGE. 
(Plate VIII.*) 
In publishing descriptions of new species of a little-known genus, 
it seemed a fit opportunity to incorporate with them the substance 
of what has already been made known upon the subject by Conti- 
nental arachnologists ; the present paper will therefore comprise the 
characters of the genus, and of the only two species of it hitherto 
known, in addition to the descriptions of the new species. 
The genus Idiops was first characterized (in 1830) by M. Perty 
(Del. An. Art. Bras. p. 197); but it appears to have been overlooked 
by Baron Walckenaer, who seems to have hastily concluded M. Perty’s 
spider to have been a species of the genus Sphasus (see Walck. Ins. 
Apt. tom. i. p. 379, Paris, 1837). It is surprising that Walcke- 
naer should not have recognized in M. Perty’s figures and lucid de- 
scription a species of a new and well-marked genus of the family 
* For description of this Plate, see the end of the supplementary paper on the 
same subject, below p. 157.—Eb. 
