3 o 4 
ERIK A : SON STENSIO 
second gill-arch; Rico, mixicoronoid; Mx, maxillary; Pc, pectoral fin; Pv, pelvic bone; do, ossifi¬ 
cations in the distal segments of certain endoskeletal radials of the A^entral fins; po, ossifications 
in the proximal segments of the endoskeletal radials of the ventral fins; pr. int, process perhaps 
developed in connection with the ligamentum interarcuale ventrale. 
Plate 24. 
Fig. 1. Birgeria mougeoti n. sp., caudal fin. (P. i5i) Somewhat less than nat. size. 
» 2. » » » » the head from above (P. i 65 ). The same as that reproduced in PI. 20, 
fig. 6, PI. 22, figs. 1, 3. 
» 3. Birgeria sp., tooth from the bone-bed 263 m above the fish horizon, Mt Bertil (P. yi 5 ). 5 / 2 . 
» 4. Boreosomus? scaber, scales ( P . 877). 3 / r 
Explanation of index letters. 
Dsph, dermosphenotic; Fr, frontal; Pa, parietal; Pro. 0, prootico-opisthotic; Stetnp. it, supra- 
temporo-intertemporal; So? supraorbital? cv, cranial cavity; hsp, haemal spines; 
Plate 25. 
Fig. 1. Glaucolepis gyrolepidoides n. sp., parts of the body preserved as impression in the stone 
{p. 6 7 1) 2 /i • 
» 2. » » » » detached scale from the bone-bed 33 m above the fish horizon, 
Mt Viking ( P . 7). */i- 
» 3. Pygopterus de geeri n. sp., small specimen lacking the dorsal parts of head and body ( P.uo ). 3 / 2 . 
Explanation of index letters. 
A, anal fin; D, dorsal fin; Icr, endoskeletal radials of the epichardal lobe of the caudal fin; 
Md, mandible; Mx, maxillary; Pc, pectoral fin; V, ventral fin; hsp, haemal spine. 
Plate 26. 
Fig. 1. Pygopterus de geeri n. sp., parts of the head and abdominal region of a rather large specimen 
(P. 112). 
« 2. » » » » » much crushed and weathered specimen (P. 671) lacking the tail 
and the posterior part of the caudal region. 3 / 2 . 
» 3. Boreosomus? scaber n. sp., scales (P. 18). i / 1 . 
Explanation of index letters. 
Bd , Basidorsal; Cl, cleithrum; Hb, parts of haemal arches; Id, clavicle; Md, mandible; Mx, 
maxillary; Nsp, unpaired neural spine; Op, operculum; Pc, pectoral fin; Po, preoperculum; R, 
endoskeletal radials of the pectoral fin; Ra, endoskeletal radials of the anal fin; Rbr, branchiostegal 
ray; Rd, endoskeletal radials of the dorsal fin; Scl, supracleithral; Sop, suboperculum; V, Ventral 
fin; ifc, supraorbital sensory canal; soc, infraorbital sensory canal. 
Plate 27. 
Fig. 1. Pygopterus de geeri n. sp., parts of the visceral skeleton ( P. iog). 
» 2. Boreosomus arcticus (A. S. Woodward) scales (/*. 6 g 5 ). 3 / r 
» 3. » reuterskioldi n. sp., parts of the body and the head. ( P. 117), mainly preserved 
as impressions in the stone. 
» 4. Platysomus nathorsti n. sp., scale ( P . §75). 
