1884. ] 583 (Cope, 
two cephalic arches, both freely movable ; (1) an anterior dentigerous one— 
the palatine, and (2) the suspensorial, consisting of the hyomandibular 
und quadrate bones ; without maxillary bones or distinct posterior bony 
elements to the mandible; with an imperfect scapular arch remote from 
the skull ; and with separately ossified but imperfect vertebre.’’ 
M. Vaillant came to no conclusion as to the affinities of this group ; and 
Messrs. Gill and Ryder remark, ‘We are unable to appreciate any affinity 
of Gustrostomus to any Anacanthines, Physostomes, or typical Apods, 
nor does it seem to be at all related to Malacosteus, which has been 
universally considered to be a little modified Stomiatid.’? Tt is, how- 
ever, clear to me that the relationships of this family Eurypharyngide 
are to the order Colocephali, and that they represent the extreme de- 
gree of the modification of structure which that order exhibits, In 
other words, the modification of the ordinary piscine type which is 
found in the Anguillide (order Enchelycephali), is carried to a higher 
degree in the Colocephali, and reaches its extreme in the Eury- 
pharyngide, The points of identity between the two groups last-named 
are so many, that it becomes desirable to ascertain whether they are 
susceptible of ordinal separation from each other. The characters 
above given to the order Lyomeri are in fact identical with those which 
define the order Colocephali, with a few possible exceptions. First, how- 
ever, I note that the supposed palatine arch, is probably the maxillary, 
as in. the Colocephali, and that it is the palatopterygoid arch which is 
absent. The five branchial arches exist in the Colocephali, but the three 
anterior are rndimental, and the basal branchihyal bones of the fourth 
and fifth are closely united. There are, however, five arches. There is a 
ceratohyal arch in Murena and Gymnomurena, but of very slender pro- 
portions. Whether this element is absolutely wanting in Gastrostomus, 
or whether the first branchial arch is its homologue, remains to be ascer- 
tained. Should the last two be coherent as in the Colocephali, we would 
then have the same number of hyoid arches in both, viz., six. The ‘“im- 
perfectly ossified cranium ’’ is shown in the detailed description given by 
Messrs. Gill and Ryder, to support the same bones which are found in the 
Murenoid skull. The degree of ossification of the skeleton does not con- 
stitute a basis for ordinal distinction, if the same elements be present. 
For this reason the perforation of the vertebral centra by the remnant of 
the chorda dorsalis does not seem to be of ordinal importance. 
In the more detailed description, there are a few charecters worthy of 
notice. First, ‘‘The notochord is persistent in the skull for half the 
length of the basioccipital.’’ This indicates further the primitive condi- 
tion of the vertebral column, but scarcely gives basis for an ordinal defi- 
nition, Second (p. 266.), ‘The neurapophyses are slender, diverging 
(instead of convergent), cartilaginous distally, and embracing the neural 
sheaths on the sides, while by the neurapophyses is supported a membra- 
nous sheath which roofs over the nervous cord,” etc. The nerual canal 
is well closed above in the Murenide, but in the Anguillide it is largely 
PROC. AMBER, PHILOS. 800. XxI, 116, 8v. PRINTED JuLY 21, 1884. 
