446 DR. GUNTHER ON THE FISHES OF CENTRAL AMERICA. 
characters of these two and of three other allied species (see ‘ Fishes,’ iv. p. 27); I had 
no faith whatever in these distinctions; but, to allow others interested in the subject to 
judge for themselves, I admitted into my account those MS. notes in the form in which 
they were sent to me. 
I was rather surprised to find in an article written by Mr. Gill a short time after- 
wards (Proc, Ac. Nat. Sc. Philad. 1865, p. 218) the assertion that the specimen sent as 
“ P. bairdii” is not this species, but the young of P. rectifrenum, “ the name, under 
which the P. dairdii was sent, having doubtless by some accident been shifted to the 
young of P. rectifrenum, and the specimen of the former lost.” If this be so, it is 
certainly curious that the “P. dairdii” sent agrees so well with the “ P. bairdii” 
described; and the shifting must have happened to the sender, inasmuch as the 
number corresponding to “ P. rectifrenum in the accompanying list” is still tied, by a 
thread drawn through the tail, to one of the specimens; and two specimens of Poma- 
centrus only having been then sent, it is fair to assume that the other example was 
meant for P. bairdii. 
But in the same paper the author goes a step further: P. dairdii is not only men- 
tioned as distinct, but it becomes one of the types of a new genus, Pomataprion, distin- 
guished from Pomacentrus by its entire’ preoperculum. In our series of examples, 
varying in size from 10 lines to 4} inches, I find that the youngest have the praoper- 
culum entire, without exception, that in specimens 2} inches long the preoperculum 
is as frequently entire as but very slightly denticulated, and that the serrature even in 
the oldest examples is fine and thin. Therefore I continue to regard those specific 
and generic distinctions of Mr. Gill as utterly valueless, and the names of P. recti- 
frenun, P. flavilatus, P. analigutta, and P. bairdii as referring to specimens of one 
and the same species. 
The synonymy stands now thus :— 
Pomacentrus rectifrenum, Gill, 1. c. p. 148. 
flavilatus, Gill, ibid. 
bairdii, Gill, 1. c. p. 149. 
analigutta, Gill, in Giinth. Fish. iy. p. 27. 
Ginther, { Pomacentrus rectifrenum, Giinth. Fish. iv. p. 26. 
1862. Heliastes insolatus, young (10 inches long), Giinth. ibid. p. 61. 
Gill { Pomacentrus rectifrenum, Gill, 1. c. p. 214. 
4 flavilatus, Gill, ibid. 
aaninialdl Pomataprion bairdii, Gill, 1. c. p. 217. 
Gill, 
1862. | 
157. HeEiastes MARGINATUS (Castelnau). 
Chromis atrilobata (Gill) is, as already stated in Fish. iv. p. 64, identical with this 
species. Mr. Gill thinks that it ought to be kept distinct on account of a “ sulphur 
spot behind the dorsal fin,” Proc. Ac. Nat. Sc. Philad. 1863, p.220. In two specimens 
1 «The praeopercular serrature is almost obsolete,” Gill, 1862, p. 149. 
