MICRO DO N. 63 



spines are comparatively stout and radiating, but the other neurals, as also the 

 haemals in the caudal region, are nearly parallel, and the only thickening occurs 

 again in the short haemals at the base of the tail. None of these arches reach the 

 dorsal or ventral border of the fish. The ribs, which are usually obscured by the 

 overlying squamation, are also stout and bear the laminar appendages or expansions,, 

 which are especially wide in the foremost of the series (PI. XIV, fig. 3, v.). Like 

 the other arches, the ribs do not extend to the ventral border. The total number 

 of vertebral arches is about 15 in the abdominal, 20 in the caudal region. 



In the pectoral arch two membrane bones are conspicuous. The clavicle is 

 relatively large, extending in a gentle sigmoid curve from the level of the noto- 

 chordal axis to the ventral border. It is constricted at the origin of the pectoral 

 fin, the upper part being narrow and tapering upwards, the lower part forming a 

 large spatulate expansion, bluntly pointed below. Its smooth inner face (PI. XIV, 

 fig. 2, d.) is concave, while its flat or slightly convex outer face (PI. XIV, fig. 1) 

 is marked by a feeble reticular ornament. The anterior border of its exposed 

 sigmoidal portion seems to bear a smooth delicate laminar expansion, partly shown 

 in PI. XIV, fig. 2, but better seen in Brit. Mus. no. 44841. The supraclavicle 

 (PI. XIV, fig. 10, scl.) is a deep and narrow bone crossed as usual at its upper end 

 by the slime-canal of the lateral line. It is widest and thickest superiorly where a 

 triangular area with a postero-inferior extension is exposed and marked with a 

 reticulate ornament. Its lower covered portion tapers to a slender point. The 

 cartilages of the pectoral arch are unknown, but the pectoral fin is lobate and 

 supported by a few long and stout hour-glass-shaped basals (PI. XIV, fig. 1). Its 

 rays are also broad and closely subdivided. The pelvic fins, of which one is seen 

 slightly displaced in PI. XIV, fig. 2, plo., are relatively small, inserted about 

 midway between the pectorals and the anal, and comprise five or six very broad 

 rays which are articulated and subdivided. The rays of the median fins are also 

 rather broad, with numerous articulations and some subdivision. There are 

 slightly more than 40 rays in the dorsal fin, slightly more than 30 rays in the anal 

 fin, and in both cases the few foremost supports are the longest and most crowded 

 to bear the long anterior rays. Unfortunately these fins are not well seen in any 

 known specimen. The characteristic forked caudal fin, with its constricted 

 pedicle, is well shown in PI. XV, fig. 2. A few of its foremost basal niys both 

 above and below are in the form of long and slender uniserial fulcra, but most of 

 its rays, about 18 in number, are articulated with step-shaped joints and also sub- 

 divided distally. All the fin-rays are smooth. 



The peculiar rod-shaped bone apparently bounding the abdominal cavity behind 

 (noticed in Catal. Foss. Fishes Brit. Mus., pt. iii, p. 196) is sometimes recognisable 

 above the hindmost ventral ridge-scale (PI. XIV, fig. 1, x.). 



As shown by the ridge-scales, the total number of transverse series of scales 

 covering the abdominal region is about 10, but they are represented for the greater 



