18 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



Stylephoridae. 



Form elongate and compressed ; the skeleton but little ossified ; dorsal extend- 

 ing from head nearly to caudal fin, its rays without cross articulations ; base of 

 pectoral horizontal and the fin inclined upward ; no anal or ventral fins ; mandible 

 enormously developed but with little movement ; mouth small, tube-like, the max- 

 illaries largely instrumental in its opening and closing ; both maxillary and pre- 

 maxillary with long processes extending over the top of cranium ; myodome 

 developed but without basisphenoid in connection ; four pairs of superior pharyn- 

 geals present, all but the first pair bearing teeth ; a greatly enlarged, pen-shaped, 

 basibranchial present, almost as long as the cranium ; post-clavicle of a single 

 piece and extending far backward ; posttemporal a simple unforked bone ; a short 

 slit behind fourth gill arch. 



Relationship. 



Stylephorus appears to be one of the many aberrant forms whose relationship 

 must remain uncertain, as the intermediate forms through which it could be traced 

 to the parent stock, have disappeared. 



The Stylephoridae has been placed by most authors with the Trachypteridae and 

 Regalecidae under the suborder Taeniosomi. Though it is at the most only dis- 

 tantly related to these families it is still more closely related to them than to other 

 known forms. 



Its affinity to the Taeniosomi is shown by the poorly ossified skeleton ; the hori- 

 zontal pectoral base ; the upturned caudal fin ; the absence of cross articulations 

 in the dorsal rays ; the reduction of the lower pharyngeals ; ^ the presence of 

 four pairs of superior pharyngeals ; and the ascending processes to the maxillaries 

 as well as to the premaxillaries. 



For comparison the characters of the Taeniosomi are here included. 



Taeniosomi.^ 



Vertebrae, hyoid arch, position of branchiostegal rays, palatoquadrate arch, 

 position of ethmoid in relation to vomer, and mouth parts normal ; the epiotics 

 in contact with each other behind the supraoccipital widely separating the latter 

 from the occipital region and the foramen magnum ; the parietals enlarged and 

 anterior in position ; an orbito sphenoid present ; ^ the post-temporal unforked 

 and suturally joined to the cranium overlying the outer half of the epiotic and 



1 Dr. Gunther reports (Cat. Mus. Brit. Mus., 1861, vol. 3, p. 306) the lower 

 pharyngeals of Trachjipterus arcticus to be wholly wanting. 



2 The characters and relationships of the Taeniosomi have been discussed by 

 Dr. Gill in the Amer. Nat. 1887, vol. 21, p. 86, and 1890, vol. 24, p. 481. 



3 The presence of an orbito splienoid would be evidence towards a Physostomus 

 origin for the two suborders here considered. 



