TRANSACTIONS OF SECTION D, 503 
The following Papers ani Reports were then read :— 
1. On the Osteology of the Lophobranchii. 
By Professor H. JuNcErsEn. 
The skeleton of the Lophobranchii has hitherto been most unsatisfactorily 
examined. The cranial structures, especially the suspensory apparatus, 
the gill-arches and the scapular arch have been incorrectly interpreted by 
all previous authors. In the skull parietals and opisthotics are wanting; 
the pterotics are greatly developed, reaching below to the basioccipital, and 
preventing the exoccipitals from meeting the prootics. These two features, 
together with the prolongation of the anterior part of the skull (mesethmoid 
and vomer), the Lophobranchii have in common with the Solmostomide, the 
Fistularide, the Aulostomide, and the Custriscide; these families form 
with the Lophobranchii one natural group, the ‘ Solenichthyes’ of Regan. 
The suspensory apparatus contains all the typical parts; only the 
metapterygoid is absent. The lower jaw is composed as usual, but the 
angular is very small; by some authors it was supposed to be wanting. 
The three opercular bones are all present; the subopercle is hidden by the 
opercle, and therefore easily overlooked (especially in Hippocampus). 
Two infraorbitals are found in the Syngnathine, three in the Hippocam- 
pine group. The hindmost infraorbital corresponds to the preorbital in 
other bony fishes. The infraorbitals do not contain any canal for the lateral 
line, neither are any of the other cranial elements nor the scutes of the 
body provided with lateral line-canals. The hyoid consists only of four 
pieces (Siphonostoma, Syngnathus, Hippocampus) or three (Nerophis). 
In the first case the ceratohyal seems to be absent, in the latter also 
the upper hypohyal is wanting. Most Lophobranchs have two branchio- 
stegals, but Nerophis has only one, which distally bifurcates.~~Glossohyal 
and urohyal are always present. In Hippocampus basibranchials are 
totally absent; in other Lophobranchii the two anterior ones are found. 
The gill-arches are slender and feebly ossified, and show a somewhat rudi- 
mentary condition. In most Lophobranchii the three anterior arches have 
epibranchials, the second and third besides possess pharyngobranchials ; 
but the epibranchials are widely separated from their ceratobranchials. 
In Nerophis no epibranchials are found, and the pharyngobranchials are 
reduced to one on each side, probably representing that of the second 
arch. The hypobranchial of the first arch is wanting in Szphonostoma and 
Syngnathus, but present in Hippocampus and Nerophis. An interesting 
step towards the condition in Lophobranchs is shown by Fistularia and 
Aulostoma when only the three anterior arches possess epibranchials, which, 
except that of the first arch, are separated from their ceratobranchials ; 
but these genera have preserved the fourth pharyngobranchial. Also a 
reduction of the basibranchials is apparent here as well as in Solenostomus. 
The scapular arch is cartilaginous to a much greater extent than is the 
case in other Teleosteans, but a small ossified scapula is found as well 
as a coracoid. The coracoid has been interpreted as two ‘interclavicles’ 
(W. K. Parker, 1868) or as one ‘interclavicle’ (Smith, 1895); the 
scapula has been totally overlooked or considered as the uppermost of five 
basals (Goodrich, 1909). In reality there are four basals, as in most 
Teleosteans. The distal ends of these bones are on each side provided 
with two or three processes bearing irregular flat expansions, which lean 
against the dermal skeleton and the dermal part of the clavicle. In this 
way the whole part on which the pectoral fin-rays play is immovably fixed 
between the lips of the slit in the armature for the pectoral fin. Through 
the narrow apertures left the tendons pass from the pectoral muscles to 
the base of the fin-rays, thus arranged between and conducted by a system 
of ‘coulisses.’ In this way the whole scapular system is strengthened by 
