42 
MMMOIBS OF TEE QVEEESLAND MUSEUM. 
patch well developed but narrow; apical teeth long; subapical elements (one 
or two rows) broader than long, with a raised phalangiform median structure,, 
corresponding to the shaft of the apical tooth. These scales are much smaller 
than those of S, maculatay and also narrower, but the structural characters exactly 
agree. 
GERRIDiE = XYST^MIDyE. 
There is also a family Gerridse in Hemiptera, based on Gerris. As the- 
insect family appears to have priority, the Gerridas of Ichthyology may take the 
name Xyst^emid^, 
Xystsema darnleyensis Ogilby. Darnley Island. Scales broader than 
long, about 5-7 mm. broad and 4^ long; about 3 to 5 widely divergent, rather 
weak basal radii; lower margin undulate; nucleus above the middle; circuli 
extremely fine and dense, transverse, confined to the region level with and below 
the level of the nucleus; apical field without sculpture; apical margin simple.. 
In some scales the nucleus is surrounded by 5 or 6 complete (circular) circuli,. 
and the circuli for some distance beyond are also circular, but cut off above at 
the level of the nucleus. The laterobasal circuli also cuiwe upwards, reaching 
the margin at a very acute angle, though the uppermost lateral circuli reach it 
practically at a right angle. 
This is a typical Gerrid (Xystaimid) scale, except that it has lost the 
last rudiments of the ctenoid patch. In Gerres rlionibeus (Mindi Cut, Panama 
Canal Zone; Meek and Hildebrand) there is a triangular w'eakly ctenoid patch, 
the lower corner elongated and pointing to the nucleus. In Eucinostomus cali~ 
for7iiensis (Mindi Cut; Meek and ITildebrand) the ctenoid patch is broad, and 
the circuli are completely transverse, even at the laterobasal corners. Thus 
E. californiemis is most specialised as to its circuli, but X darnleyensis has 
gone farther in the direction of the loss of ctenoid elements. 
POMACENTRIDxE. 
Amphiprion percula L. Darnley Island. Scales subquadrate, about 
1 mm. broad and f mm. long ; nucleus a little above the middle ; basal radii 5 to 
C very distinct; basal margin crenate or scalloped; circuli normal; ctenoid 
patch very v^ell developed; marginal teeth sharp, with broad bases. 
These differ from other Pomacentrid scales seen in having the circuli 
relatively much less dense, and the lateral margins of the apical teeth more or 
less concave instead of straiglit. The subapical ctenoid elements are inclined 
to be more or less bottle-shaped. 
EPHIPPID.E. 
Scatophagus setate varians de Yis. Queensland. Scales very small, 
diameter about 1-1-| mm. ; quadrate, as broad as long, or considei’ably broader 
