298 32 



uous ethmoidal cartilage found in the embryo and larva; during growth and ossi- 

 fication the cartilage is replaced by bones, only this small anterior median part 

 and two basal lateral parts, each enclosed in the prefrontal (ectethmoid), being 

 preserved. 



The supraoccipital is in front wedged in between the frontals, behind it sends 

 out a short, downwards directed nuchal process, connected through ligament with 

 the anterior nuchal plate. The posterior margin of the epiolic projects like a crest, 

 below which the strong tendon for part of the anterior lateral muscles is attached. 

 Parietals and opisthotics are wanting. 



The mesethmoid takes up more than half the length of the snout. The 

 posttemporal (pt) is connected with the epiotic, pterotic and exoccipilal; its 

 pointed posterior end is bound to the front end of the clavicle by connective 

 tissue. 



On the lateral aspect the same bones are seen (PI. V, fig. 4). On the posterior 

 aspect (fig. 3) the exoccipitals meet each other above the foramen magnum as in 

 Aulostoma and Fistularia and latei-ally each exoccipital projects into a process be- 

 low the foramen, carrying an articular face for the process on the first vertebra. 

 The condylar face is conicaliy hollowed as usually; the margins of the hollow are 

 stouter than the corresponding margins of the vertebrae. 



On the lower aspect of the skull (PI. V, fig. 2) the very large pterotics (sq) are 

 particularly conspicuous, ventrally reaching the basioccipital (ob) and preventing 

 the exoccipitals from meeting the prootics (pro). Between part of the latter and 

 the basioccipital (ob) a cartilage is seen. The foramina for the nerves in the pro- 

 otics are situated quite as in Aulostoma and Fistularia, those of the 5th nerve in 

 the front face, towards the orbit, those of the seventh laterally (as typical in true 

 Acanthopterygians); and the anterior articular surface for the hyomandibular also 

 here belongs partly to the postfrontai, partly to the prootic, while the posterior be- 

 longs to the pterotic alone. A sharp ridge divides the part of the prootic visible 

 from below from that looking towards the orbit; with this ridge a ligament from 

 the hyomandibular is connected. 



The parasphenoid (pa) is elongated, reaching farther in front than in Aulo- 

 stoma and Fistularia, and connects in a long triangular suture with the vomer; it 

 possesses a considerable orbital part, joining the frontal above and lateially bound- 

 ing the fossa for the inferior musculi recti of the eye. A true "myodoma" is not 

 developed, the prootics from both sides not meeting completely to form a bony roof 

 over the origin of the eye-muscles. 



The front end of the vomer is somewhat heart-shaped, edentulous; for a long 

 way it is joined to the concave under face of the mesethmoid and its needle- 

 shaped hind part reaches along the parasphenoid to the level of the prefrontals. 

 The orbital wall of the brain-case is formed by the parasphenoid, prootic, 

 postfrontal, alisphenoid (the latter, being small, is easily overlooked) and the 

 frontal. 



