TRIASSIC FISHES FROM SPITZBERGEN 
127 
Only two ossifications are known in the Meckelian cartilage, namely the articular 
and the autangular, both comparatively small. The membrane bones of the mandibula 
consist of a supraangulo-angular, dental, splenial, coronoid, intercoronoideo-prearticular 
and two or three precoronoids. 
The supraangulo-angular is a large bone, apparently arisen by fusion of thehomologues 
of the angular and supraangular of the Rhipidistids and possibly one or more of their so- 
called infradentals as well. Sometimes it has a fairly high, triangular shape (Axelia, Myla- 
canthus), sometimes, on the other hand, it is low and long. The dental and the splenial are 
both fairly short and low. The coronoid is fairly large and often triangular. The intercoro¬ 
noideo-prearticular covers the inside of the mandible from the symphyse almost to the posterior 
end. To its upper margin the coronoid is joined posteriorly and the precoronoids anteriorly. 
The conditions of the maxillary and premaxillary are still rather uncertain. As a 
maxillary I have, however, provisionally interpreted a narrow bone in Wimania sinuosa , 
which lies loose in relation both to the pterygoid and the lacrymo-jugal. It is also 
possibly present in Coelacanthus (Wellburn 1902). 
In the hyoid arch there appear two ossifications, a long and powerful one in 
the ceratohyal and a smaller vertical one in a segment situated dorsally of this, which 
may probably be considered to correspond to the epihyal. If a hyomandibular was 
developed, it must have been cartilaginous, relatively small and probably only corresponded 
to a pharyngobranchial (cf. Allis 1915). The ceratohyal ossification always has a typical 
rounded projection on the ventral margin. 
The opercular apparatus consists only of a large plate called the opercular. This 
plate is especially large in the Palaeozoic and Triassic forms. Its postero-ventral margin 
may sometimes show a spiny or lobed shape (Mylacanthus). 
Between the mandibles there are always two large, well developed jugular plates, 
more or less elongated in shape. 
Five pairs of branchial arches are usually present. In Macropoma, however, there 
are said to be only four. In them there constantly appears a long ventral ossification, 
probably corresponding to a ceratobranchial and a dorsal one, possibly representing 
both the epi- and the pharyngobranchial. Both ossifications have generally had cartilaginous 
epiphyses. The ceratobranchialia are characterized by a deep longitudinal furrow on 
their posterior side. 
The ventral ends of the branchial arches have been connected by a cartilaginous 
copula. It is of course impossible to decide whether this in its turn consisted of a uniform 
piece of cartilage or was divided into segments. It was covered by a number of tooth 
bearing plates, sometimes very thick and strong as is the case in Axelia, Mylacanthus 
and Scler acanthus. 
As in the Actinopterygii a large and strong urohyal is found developed. 
Dentition. — The precoronoids and the bone interpreted as a maxillary has, at least 
in the majority of Coelacanthids, rather large conically pointed teeth. The parasphenoid, 
the plates on the copula, the pterygoid, the dermopalatine, the intercoronoideo-prearticular 
and the coronoid generally have small teeth more bluntly conical or sometimes even 
rounded. The dentition of the branchial arches consists of small plates furnished with 
small and more or less pointed conical teeth. 
