Lava-Flow Fishes — Gosline 
379 
Fig. 4. First vertebra and ribs of, a, Otophidium 
and, b, Brotula, from front. Surfaces for articulation 
with skull hatched, na, Neutral arch; ri, rib; sp, space 
containing spinal cord. 
terminology will be used in order to deal with 
character no. 13 of Table I. In Brotula the first 
five vertebrae have "sessile ribs”; in Dinematich- 
thys the first six; in Otophidium the first, third, 
fourth, and fifth; and in Snyderidia the first 
three only. (In Microbrotula ribs are now lack- 
ing from several of the front vertebrae, but they 
may well have been lost in the process of skele- 
tonization.) Judging from Emery’s plate (1880, 
pi. 5) sessile ribs are present on the first four 
vertebrae of "Fierasfer acus” and "Fierasfer den- 
tatus”; in the latter species each rib is separate, 
but in the former the ribs of vertebrae three and 
four have apparently fused into a single plate 
(see also Arnold, 1956, fig. 2c). According to 
Arnold (1956: 257, fig. 5) a third group of 
carapids has the transverse processes ("sessile 
ribs”) of vertebrae three, four, and five fused 
into a single plate. 
Regan has also used the number of "strong 
transverse processes” as a character for separat- 
ing the brotulids from the ophidiids (Table 1, 
no. 14), but this is certainly a variable char- 
acter in the brotulids. For example, Microbro- 
tula has transverse processes only on vertebrae 
eight through eleven, whereas Hypoplemon (see 
Radcliffe, 1913, pi. 14) has greatly expanded 
parapophyses on vertebrae four to fourteen 
(which partly enclose the air bladder). 
A final vertebral character is the number of 
abdominal and caudal vertebrae (Table 1, no. 
12). In the three brotulids skeletonized counts 
are: Brotula, 15 abdominal + 46 caudal; Micro- 
brotula , 12 + 40; Dinematichthys, 12 + 34; 
in Otophidium, 16 + 53; in Snyderidia, 15 + 
58. Emery (1880: 26) gives 125-144 vertebrae 
for "Fierasfer acus” of which 17 or 18 are 
abdominal. Arnold (1956) uses the number of 
trunk vertebrae as one basis for dividing the 
carapids into three sections, one group having 
17-20, another 27 or 28, and a third 30 or 31. 
Internal soft anatomy : The air bladder of 
Snyderidia is apparently simple and extends 
from below the second to below the twelfth 
vertebra. According to Gilbert (1905: 654) 
Snyderidia has two pyloric caeca. 
External characters: Only a few of the ex- 
ternal features of Snyderidia need be noted. First, 
the species resembles the carapids in the pres- 
ence of a long tail that tapers gradually to noth- 
ing. Second, though the pectoral of the lava 
flow specimen of Snyderidia has been rather 
badly frayed, it is possible to count 27 rays on 
one side. This high count seems to place Sny- 
deridia with the brotulids and ophidiids rather 
than with the carapids (Smith, 1955: 546). 
Finally, there are no scales whatever. 
Relationships: On the basis of the foregoing 
comparison Snyderidia would appear well dif- 
ferentiated from the Ophidiidae, Brotulidae, and 
Carapidae, but is probably closest to the last. 
Especially notable carapid characteristics in Sny- 
deridia are the absence of pelvic fins, the long 
anal fin, the tapering body, the lack of scales, 
and perhaps especially the dentition. Indeed, in 
all these respects and notably in lower jaw struc- 
