1870. ] HANCOCK AND HOWSE—DORYPTERUS HOFFMANNI. 627 
smooth, without striz or granulations; but their appearance is not 
very distinct. The hind border of the operculum or gill-plate is 
narrow ; near to it is placed the left pectoral fin, which has probably 
been pushed so high up by pressure from without. One recognizes 
only the impressions of a few rays: below, on the margin near the 
anal, the rays of a small fin are shown, which appear to have be- 
longed to the ventral; for although, until now, on the specimens of 
the genus Platysomus which have been examined by Agassiz, 
Germar, and others ventral fins have not been seen, yet I have found 
them on two examples of P. Fuldai (= Platysomus macrurus, Ag.). 
<< The dorsal fin is somewhat large ; the commencement of it is near 
the head, in the central part of the back. The anal stands opposite 
to it, and is nearly of the same form and size, but is situated nearer 
to the mouth than to the tail; for it reaches nearly to the head. 
The rays of both fins run to the tail, and are very fine. On the ex- 
ample before us, fragments only of the rays of the continuation of the 
dorsal could be seen. 
“The pedicle of the tail is remarkably narrow, only about a line 
broad; the deep-forked fin is proportionally very large. Of both 
lobes the extremity is wanting; but it seems that the upper lobe was 
not mueh longer than the lower, which is a little broader. 
“< There is, as mentioned before, no trace of the scales.” 
In Minster’s figure of P. Althausiz, the posterior part of the body, 
allowing for the slightly different state of preservation, much resem- 
bles ours. The form of the abdominal cavity, bounded in front by 
the “‘ ribbon-shaped process,” and posteriorly by the abdominal rod, 
is identical. The position of the pectoral fin is also the same, 
though thought by Miinster to have been disturbed and pushed 
upwards out of its true position. The prolongation of the dorsal fin 
is destroyed, as in most of our specimens ; and the bones of the head 
are much displaced, and moved downwards and backwards towards 
the ventral cavity ; but these bones are said to be smooth and with- 
out striz or granulations—a character which at once distinguishes 
this fish from Platysomus, in which the bones of the head are always 
more or less ornamented with granulations or striz. 
In Minster’s example the anal fin is finely preserved, and shows 
very distinctly its continuation to the tail; but by displacement and 
pressure of the bones of the head downwards, the ventral fins, which 
Mister saw, but could not describe rightly on account of the dis- 
turbed state of his specimen, have been pushed backwards, and 
brought nearly into contact with the anal fin; and thus one of the 
striking peculiarities of Dorypterus (the thoracic or jugular position 
of the ventrals) remained till now unobserved. It will, we think, 
be admitted by every one who carefully collates Miinster’s figure 
and description of P. Althausii with those of Germar’s Dorypterus 
Hoffmanni, that they are perfectly identical; and we adopt the 
latter name for the species, as it has a slight precedence in order 
of description, and was, besides, more strongly characterized than 
‘the former. 
The German specimens of Dorypterus were obtained from the 
