296 Transactions.—Zooloyy. 
Key to the Species of Regalecus. 
A. More than 250 dorsal rays. 
a. Teeth present: a caudal fin (?). 
a. Height = 4, length ... St e. 1. A. gladius. 
B ow = 4 4 i t PES QSR? telum. 
b. Teeth absent : no caudal em 
a. Height = +; length : ne e. 8 R. banksi. 
a ae et D. 406 ... we 4. Ri grilla. 
B. Fewer than 250 dorsal rays. 
a. Teeth present (?): a caudal fin va 
D. 135 — rio T e. 6. R: glesne. 
b. Teeth absent. 
a. A caudal fin: D. = E i .. 6. R. russellii. 
B. No caudal fin. 
i. Height = 7, length: D. 8, ... 7. R. pacificus. 
He UI, D. 75 .. 8. R. argenteus. 
EXPLANATION OF PLATES XXIII. AND XXIV. 
Prate XXIII. 
Fig. 1. Regalecus argenteus, side view of the head (} nat. size). 
br, branchiostegal rays: d. 21, first ray of 2nd dorsal fin: e, eye: fr, preorbital 
process of frontal bone : y, gills: is, isthmus : i.op, inter-opercular : le, lachrymal 
bone: 1.1, lateral line: mn, mandible: mz, maxilla: na, nostril : op, opercular : 
pe. f, pectoral fin: p.e, par-ethmoid (pre-frontal) : p.mz, pre-maxilla : p.op, pre- 
opereular: pv. f, pelvic (ventral) fin: r. 7, seventh, and r. 9, ninth rays of crest : 
s.0p, sub-opercular. 
Fig. 2. Regalecus argenteus, distal Aves of 7th ray of crest (nat. size) ; x, point at which 
membrane became bro 
Fig. 3. Regalecus argenteus, id section through the body, at entra the middle 
(+ nat. size). 
d.f, dorsal fin: g.c, gastric cecum: h.a, hemal arch, enclosing caudal artery an 
vein ; 1.1, lateral line : n.a, neural arch, enclosing spinal cord : r.r, tuberculated 
ridges: v, centrum of vertebra. 
Prate XXIV. 
after von Haast. 
. ” ” 
3. Head of R. banksii, after Hancock and Embleton. 
di. j » C), from Gray. 
5. ” ” (?), ” 
» . KR. gladius 
” | 
Fig. 1. Head of R. x 
after Cuvier. 
} trom Yarrell, after Bohmeider, 
