— 198 — 



of the recess. The membranes closing this recess toward the cranial cavity were not investigated, 

 but the recess is certainly a myodomic recess, similar to, and as well developed as, that recess in 

 Gadus. Uranoscopus thus has a myodome of the kind found in Gadus. It furthermore has a proötic 

 vacuity larger even than the vacuity in Gadus, and which, as in Gadus, extends posteriorly into 

 the anterior end of the basioccipital. 



In Blennius gattorugine the posterior portion of the ventral edge of the proötic is thick and 

 grooved, the mesial edge of this groove representing the mesial process of the bone, and the other 

 edge representing the ventral portion of the body of the bone. Anterior to the groove the actual 

 ventral edge of the bone is formed by the mesial edge of its mesial process. This edge of the bone, 

 as also both edges of the posterior, grooved portion, are widely separated from the corresponding 

 portions of the bone of the opposite side, the space between the mesial processes being bridged by 

 a membrane which underlies the hypoaria and pituitary body. Anteriorly, this membrane is attached 

 to the hind edge of the basisphenoid, that bone being, in this fish, unusually wide in an antero-posterior 

 direction. Beneath this membrane and the basisphenoid, between them and the underlying para- 

 sphenoid, there is a long and relatively large space which lodges certain of the eye muscles and is 

 accordingly a well developed and perfectly normal myodome. The pituitary opening and the hypo- 

 physial fenestra are simply unusually large, and the pituitary opening lies much further posteriorly 

 than in Scomber and Scorpaena. 



In Lophius piscatorius there is, in the prepared skull, no myodome, as Vrolik has stated. 

 In the fresh skull, however, there is a pocket between the bony floor of the skull and an overlying 

 membrane, and in this pocket certain of the eye-muscles have their origin. The pocket is accordingly 

 a myodome. The overlying membrane is thick and strong, and forms the hind wall of the orbit as 

 well as the roof of the myodome. Laterally, on either side, it extends upward and forms, as in Amia, 

 the mesial wall of the trigemino-facialis Chamber. The membrane is thus similar to that in Amia, 

 but it is even more extensive than in that fish, for it entirely replaces, in Lophius, the bony mesial 

 processes of the proötics. 



In both Syngnathus and Hippocampus, which I have examined in serial sections, there is a large 

 myodome, roof ed, in Syngnathus, entirely by membrane, while in Hippocampus the recti externi extend 

 backward beyond the other muscles and pass beneath the cranial floor, between it and the parasphenoid. 



In Gymnarchus, of the Mormyridae, a dilapidated skull of which I have, there is apparently 

 no myodome, the conditions here being similar to those found in Ameiurus, which will be later de- 

 scribed; but in two other members of the family, Mormyrops deliciosus and Petrocephalus bane, 

 Ridewood ('04b) says there is a myodome. 



In Osteoglossum Leichardti and Heterotis niloticus, of the Osteoglossidae, Ridewood ('05a) 

 says there is a myodome; as there also is, according to the same author, in Pantodon Buchholzi and 

 Phractolaemus Ansorgii. 



In Galaxias of the Galaxiidae, Swinnerton ('03) says there is a myodome. 



In Pleuronectes platessa, Cole & Johnston ('01, p. 13) say there is a myodome. 



In Echeneis, of Boulanger's Discocephali, I find, ventro-antero-mesial to the trigemino-facialis 

 Chamber, a large aperture, which, in the prepared skull, leads directly into the cranial cavity, along 

 its floor. The aperture is bounded dorso-mesially by a bone that must be the basisphenoid, although 

 the sutures in this region can not be distinguished in my one specimen; and from the hind edge of 

 this bone a strong membrane extends, in the recent State, backward and downward and is attached 



