GREGORY: FISH SKULLS 



257 



In Lachnolaimus (Fig. 130) the deepening of the head brings the quadrate-articular 

 joint down to a low level, thus increasing the area of the adductor mandibulae muscles 

 and lengthening the ascending processes of the premaxillse. In the highly specialized labrid 

 Epibulus as described by Delsman (Fig. 131) the mouth is excessively protrusile. All the 

 conditions mentioned above on page 256 here reach their maximum. Besides this, even 

 the quadrate has acquired a loose joint with the hyomandibular and can now be swung 

 forward to aid still further in the extreme protrusiiity of the mouth. According to Tate 



Epibulus 



Fig. 131. Epibulus. After Delsman. 



Regan (1913fl, p. 133; 1924, p. 205) this form is closely related to the labrid Cheilinus, 

 in which the mouth is only moderately protractile. 



A peculiar specialization, perhaps from a Lachnolaimus-WVt ancestor, is seen in Iniistius 

 (Fig. 132) of the family Coridse. Here the face has been greatly deepened beneath the 

 orbit. The jaws are short antero-posteriorly and deep vertically, with prominent curved 

 hook-like incisors and small pointed-conical cheek teeth. The opercular, sub- and inter- 

 operculars are membranous. The opposite specialization is seen in the labrid genus Gom- 

 phosus, which has the face elongated antero-posteriorly int9 a tubiform snout (c/. Jordan 

 and Evermann, 1905, p. 289). 



The otoliths of the labriform division, according to Frost (1928a, p. 452), are special- 

 ized and differ from the percid type. Those of Iniistius are very aberrant. 



Scarids. — In the parrot-fishes (Scaridae) the premaxillary and dentary teeth are fused 

 respectively into an upper and a lower beak (Fig. 133). In the more primitive genera 

 the relations of the premaxilla, maxilla and dentary differ from those in the wrasses, chiefly 

 in the fact that the beak is shortened and brought back near the quadrate-articular pivot. 

 In the mandible of certain genera a secondary joint is formed between the dentary and 



