MORPHOLOGICAL METHOD AND RECENT PROGRESS IN ZOOLOGY. 595 



In the fishes, where the pericardhiin is ulone sliut oli', the retcMitioii 

 of the iiuunniiilian terms but hampers progress. This was indeed 

 felt hy Dumeril when, .in 1>SH5, he attempted a revisionary scheme. 

 Since, however, one less fantastic than his seems desiralile, 1 would 

 propose that for tlu> future the ""anal"" lin be termed venti'al, the 

 "ventral" pelvic, and that for the several positions of the pelvic, that 

 immediately in front of the vent, primitive and eml)ryonic (which is 

 the position for the Elasmobranchs, Sturiones, Lower Siluroids, and 

 all the hioher Vertebrata), be termed proctal, the so-called ''aljdomi- 

 naV pro-proctal, the so-called '"thoracic'' jug-ular (in that it denotes 

 association with the area of the "collar ])one"), and the so-called 

 "jugular"" mental. Th(^ necessity for this becomes the more desirable 

 now that it is known that a group of Cretaceous fishes (the Ctenothris- 

 sida'), hitherto regarded as Berjx-oids, are in reality of clupcoid 

 affinity, despite the fact that at this t^arlv geologic period they had 

 translocated, their pelvic fin into the jugular ("thoracic'"') position. 



The sum of our knowledge acquired during the last twentA'-eight 

 years proves to us that among the bony fishes the structural combina- 

 tion which would give us a premaxillo-maxillary gape dentigerous 

 throughout, a proctal pelvic fin, a heart with conal valves, would be 

 the lowest and most primitive. Inasnmch as this character of the 

 heart, so far as at present known, exists only among the Clupesoces 

 (pikes and herrings and their immediate allies), these must be regarded 

 as lowly forms, wherefore it follows that the possession of but a single 

 dorsal hn is not, as might appear, a necessary index of a highly modified 

 state. 



Before I dismiss the vertebrates, a word or two upon a recent result 

 of morphological iit(|uiry which concerns them as a whole. I refer to 

 the development of the skull. Up to 1878 it was everywhere thought 

 and taught that the cartilaginous skull was a compound of paired 

 elements, known as the trabecuhv cranii and parachordals, and that 

 the former contributed the cranial wall. Huxle}^ in 18T-I-, from the 

 study of the cranial nerves of fishes, had reiterated the suggestion he 

 made in ISOi, when dealing with the skidl alone, that the trabecuhy 

 might be a pair of pra^-oral visceral arches, serial with those which 

 support the luouth and carry the gills. The next step lay with the 

 sturgeon, in which, in 1878, it was found that the cranial wall is orig- 

 inall}' distinct. And latei', when the facts were mon; fully studied in 

 sharks, ])atrachians, reptiles, and birds it became evident that the 

 trabeculie, though ultimately associated with the cranial wall, take no 

 share in its formation, and that when first the}' ap})ear they arc dis- 

 posed at right angle's to the parachoixlals and the axis scM'ially with 

 the visceral arches behind. Huxley was right, and although this con 

 sideration by no means exhausts the cat(\gory of independent carti- 

 lages now known to contribute to the formation of the skull, it proves 



