453 
the peculiar hinge structure of Avicula Barlelyi, so far as I have heeu able to ascertain. 
There is a resemblance, however, with Pseudomonot is^ Beyrich,* in the proportion of 
the valves, deeply cleft pseudo-ear, and strong byssal sinus ; but in the type, P. 
spelunoaria, there is no posterior wing, but an irregular auriculate end, without any 
parallel in the Queensland shells. Especially does approach those shells from the 
Carboniferous Series of the Salt Range, in India, described by Dr. A. Waagen,t such as 
Pseudomonotis garforthensis, King,J or P. hizanensis. Even Waageu’s species differ a 
good deal from P. spelunoaria, and I much question if they can be regarded as true 
members of the genus Pseuiomonoiis. We are unable to discover from Waagen’s 
remarks that the hinge structure of his shells and Avicula BarJclyi, Moore, in any way 
agree in detail. His description of P. kazanensis is as follows : — “ The hinge is very 
simple. It shows in the middle a somewhat triangular emargiuation, very likely for the 
reception of a cartilage. Anteriorly to it there is a broad facet, which reaches to the 
end of the anterior wing. Its lower margin is somewhat prominent, and forms a kind 
of very indistinct elongated tooth. Posteriorly to the ligamental groove the hinge-line 
is simply thickened.” 
The nearest ally of Maccoyella, so far as my researches have yet gone, is 
Undoubtedly Whitfield’s Meleagrinella,^ typified by Avicula curia, Hall.|| The 
resemblance lies in the general appearance of the two genera, the presence of a deeply 
cut-off ear in the right valve, and the thickened area of the left valve. But the 
structure of the divided ear and hinge-line of the right valve is wholly different, as the 
following quotation will show. Speaking of the byssal fold, Whitfield says it is 
either a deep channel on the external surface of the shell extending from the margin 
to near the beak of the valve, or a simple deep straight notch separating the wing into 
u linear process, of greater or less length, from the body of the shell.” There is no 
structure hero corresponding to the inflection or fold of the hinge iu the right valve 
of Maccoyella, nearly central iu position, whereas the byssal fold of MelcagrincUa is 
anterior. In addition to this, the inequality in the size of the shell in the two genera is 
most marked. Under these circumstances I believe I am justified in separating 
Moore’s shells as the types of an undesoribed genus. 
The whole group of species, but more especially the type, M. Barklyi, bear 
m their external appearance a marked resemblance to some inequilateral forms of 
llinnites, such, for instance, as II. Studeri, Pictet and Roux, from the Gault of St. 
Croix.^ 
The number of species referable to Maccoyella is at present open to doubt. 
Moore described the following under the name of Avicula : — Avicula Barklyi, A. refiecta, 
umhonalis, A. corhiensis, A. mhstriata, A. simplex, and A. cequalis, but the two last 
may be at once dismissed from consideration. The late Rev. J. E. T. Woods** clearly 
'Considered the whole as varieties of one species. He wrote : “ Anyone who examines 
fhe series figured by Mr. Moore from Wollumbilla, including eight species, will be 
inclined to refer them all to one, differing from each other merely in size and mode of 
growth.” With all due respect to' this adverse opinion, it is not so easy to refer all of 
* Zeitsch. deutsehen Geol. Gesellsoh., 18G2, xiv., p. ]0. 
t Pal. Iiidioa (Salt Kange Posails), Vol. i., 1881, Pt. 3, p. 270. 
$ Loc. ait., t. 22, f. 2. 
p § Mon. U.S. Geol. Survey (Powell’s), 1885, ix. (Raritan Clays and Greensand Marls of New Jersey), 
f 9n Survey (Powell’s) Rooky Mountain Region (Pal. Black Hills of Dakkota), t. 3, 
• « 0 - 25 , 
^ Pal. Suisse, 5me. Sdrie, line. Pt., p. 232, t. 179, f. 1. i 
**Proc. Linn. Soc. N. S. Wales, 1883, viii., Pt. 2, p. 240. 
