do not possess a basisphenoid. It is indeed food for 

 thought that a basisphenoid occurs only in Triodon, 

 which by all odds is the most primitive of the Recent 

 gymnodonts, and in molids, which are one of the end 

 lines of gymnodont radiation. Starks (1905:755), in dis- 

 cussing the myodome of fishes, noted that "the dichost 

 ( = basisphenoid of Huxley) is always absent when the 

 myodome is. I know of no case where it is at all ossifed 

 when the myodome is absent." Molids are thus an ex- 

 ception to the rule. The basisphenoid of Triodon is 

 relatively normal in appearance, but that of molids is ex- 

 panded anterodorsally until it makes contact with the 

 pterosphenoids (in Mola and Masturus) or frontals (in 

 Ranzania). 



In the ethmoid region the size and shape of the eth- 

 moid have been prominently used in the classification of 

 the tetraodontids by Fraser-Brunner (1943). While the- 

 ethmoid of tetraodontids is sometimes rather small, by 

 far the most reduced state of the bone is found in diodon- 

 tids, where there is a thin plate of bone that represents 

 the only remains of the ossifications of the entire eth- 

 moid region of the skull in a position analogous to that of 

 both the vomer and the ethmoid. For that reason, this 

 bone is called here the ethmoid-vomer, supposing that it 

 represents the fused rudiments of both elements. Starks 

 (1926:286) recognized the dual anatomical position of 

 this bone in Diodon, but preferred to call it the ethmoid. 

 It should be mentioned briefly that in HoUard's various 

 publications the medial portion of the plectognath eth- 

 moid was called the "ethmoid," while its lateral por- 

 tions were referred to as the "nasals." Hollard did not, 

 however, show any sutures between these two regions, so 

 his terminology was undoubtedly based on theoretical 

 considerations. Awati and Bal (1933) divided the eth- 

 moid of their tetraodontid in the Hollardian manner, but 

 referred to the medial portion of the ethmoid as the 

 "lateral ethmoid" and to the lateral portions of the eth- 

 moid as the "nasals." Swinnerton (1902) found the eth- 

 moid and palatine regions of balistids and acanthurids to 

 be similar. 



The vomer of tetraodontids and ostracioids is some- 

 times so closely interdigitated, or even fused, with the 

 ethmoid and parasphenoid that even a relatively knowl- 

 edgeable worker such as Kaschkaroff (1914a:350) mis- 

 takenly said that the vomer was absent in those groups. 



In the mandibular region the presence of a symplec- 

 tic has sometimes been overlooked. Cope (1871:591) 

 stated that in the Phyaoclisti "the symplectic is present, 

 except in Ostracion, where it is not ossified," but Regan 

 (1903a:290) corrected Cope's error. In view of Regan's 

 statements, it is surprising to find that Kaschkaroff 

 (1914a:352) extended Cope's misstatement to include 

 Triacanthus as well as Ostracion, both of which Kasch- 

 karoff said lacked a symplectic. Raven (1939b:4) said that 

 the symplectic was absent in Ranzania, but figures 316 

 and 320 given here show it to be long and prominent. 



In the palato-pterygoid region the size, shape, and 

 articulations of the palatine have been used as impor- 

 tant diagnostic features for a number of plectognath 

 subgroups, sometimes erroneously. A summary of the 



condition of the palatine in plectognaths, with brief com- 

 ments on the literature, follows. In triacanthoids the 

 palatine is basically a flattened rectangular or squarish 

 bone with a small posterodorsal lobe about midway along 

 its upper edge for firm anchoring through fibrous tissue 

 with a region of the ethmoid-prefrontal-vomer, while 

 ventrally the palatine is firmly anchored by fibrous tis- 

 sue with the ectopterygoid, except in the long-snouted 

 species in which it forms a portion of the tubelike snout; 

 an anterior process of the palatine movably articulates 

 with the recessed dorsolateral surface of the maxillary so 

 that the latter can rotate around this articulation and 

 allow for a slight protraction of the upper jaw, except in 

 the long-snouted species in which the protractibility of 

 the upper jaw is not so directly associated with a maxil- 

 lary-palatine articulation. In balistids what is the squar- 

 ish ventral portion of the palatine in most triacanthoids 

 becomes shaftlike and the whole palatine T-shaped, 

 with the ventral shaft firmly anchored by fibrous 

 tissue with the ectopterygoid, the posterodorsal end 

 similarly held to the ethmoid and vomer, and the antero- 

 dorsal end movably articulated with a slight concavity 

 on the lateral surface of the maxillary, around which 

 point of articulation the upper jaw rotates, without being 

 protracted. In monacanthids the palatine is rodlike, but 

 sometimes with a bulge on its ventral surface represent- 

 ing the long foot of the T as found in balistids, con- 

 nected ventrally by a long ligament to the anterior edge 

 of the ectopterygoid, while posteriorly the rod is 

 anchored by fibrous tissue to the ethmoid and anteriorly 

 is movably articulated with a slight concavity on the 

 lateral surface of the premaxillary and maxillary. 



The differences in the shape of the palatine in the tria- 

 canthoids, balistids, and monacanthids have long been 

 known, but with Regan's (1903a) use of these features as 

 diagnostic characteristics an error crept into the 

 literature. Regan said that the triacanthoids had the 

 palatine immovably articulated with the other bones of 

 the skull, but that the balistoids had it either movably 

 articulated with the ectopterygoid (balistids) or entirely 

 free from it (monacanthids), and Fraser-Brunner (1941b) 

 has said much the same thing. The differences in the 

 shape of the bone are real enough, but the palatine im- 

 movably articulates with the ectopterygoid and with the 

 ethmoid-vomerine region in all of these groups. It is the 

 firm anchoring of the palatine to these two regions which 

 provides the upper jaw with the immovable prop around 

 which it can rotate. The ventral edge of the palatine and 

 the dorsal edge of the ectopterygoid in triacanthoids and 

 balistids are often not in close contact with one another, 

 but the sheet of tough fibrous tissue that binds the 

 palatine to the ectopterygoid and to the ethmoid- 

 vomerine area makes the palatine immovable for all 

 practical purposes. 



In ostracioids the palatine is a relatively small and 

 elongate block of bone, representing an enlarged foot 

 of the T-shaped balistid palatine, which is usually 

 extensively interdigitated with the dorsal end of the 

 ectopterygoid and mesopterygoid. The rounded dorso- 

 medial edge of the palatine is firmly held by fibrous 



