SCIENCE. 



149 



Odontolcae, and Odontotormae and absent from recent 

 birds, are the narrowness of the proseiicephalon, the 

 persistent separation of the mandibular rami and the 

 presence of teeth. 



That the presence of teeth has been regarded by 

 Prof. Marsh as the principal — if not the only essential 

 — characteristic of the Odontornithes, is indicated by 

 the following passages from the present work, or from 

 previous papers. 



tooth of Hesperornis Regalis, showing germ of young tooth. 



" Both of these types possessed teeth, a character 

 hitherto unknown in the class of birds, and hence 

 they have been placed by the writer in a separate sub- 

 class, the Odontornithes." P. 3. 



" That Archaopteryx belongs to the Odontornithes, 

 the writer fully satisfied himself by a personal exam- 

 ination of the well-known specimen in the British 

 Museum. The teeth seen on the same slab with this 

 specimen agree so closely with the teeth of Hesper- 

 ornis, that the writer identified them at once as those 

 of birds and not fishes." P. 186. 



In speaking (p. 191) of the "bird remains found in 

 the Green-Sand deposits of New Jersey," our authoi 

 says ; " as neither jaws nor teeth have yet been de- 

 tected, it is at present impossible to say whether the 

 Eastern species belong to the Odontornithes." 



Before the discovery of the teeth, he had character- 

 ized the Hesperornis regalis as a "gigantic diver re- 

 lated to the Colymbidae." His preliminary description 

 of the same bird had been to the same effect, with the 

 addition " that it differs from the Colymbidae so 

 widely in the structure of the pelvis and posterior 

 limbs as to demand a place in at least a separate 

 family." 



In the present publication, however, our author is 

 of opinion that " the struthious characters seen in 

 Hesperornis should probably be regarded as evidence 

 of real affinity, and in this case Hesperornis would be 

 essentially a gigantic swimming ostrich." P. 114." 



That Prof. Marsh's opinion as to the taxonomic 

 value of the teeth is shared by zoologists generally, 

 is shown — at least negatively— by the absence of dis- 

 sent from his own views and from those of such re- 

 viewers as Newton and Woodward. The former 

 speaks of the " teeth, whence the Ichthyornis has been 

 made the type of a distinct sub-class." The latter, 

 writing of the same genus, says : " The possession of 

 teeth and biconcave vertebrae, although the rest of the 

 skeleton is entirely avian in type, obviously implies 

 that these remains cannot be placed in the present 

 group of birds, and hence a new sub-class. Odontorn- 

 ithes is proposed for them." In the added note, re- 

 specting Hesperornis, Woodward does not state 

 whether he was then aware that the vertebrae of that 



genus lacked the biconcave character. Hence it is 

 not certain whether he would regard it as an odon- 

 tornith by reason of the teeth alone. 



Prof. Huxley does not distinctly mention the degree 

 of separation of the toothed birds from the rest, but 

 he says that the Hesperornis regalis " in a great many 

 respects is astonishingly like an existing diver or 

 grebe, so like it indeed, that had this skeleton been 

 found in a museum, I suppose — if the head had not 

 been known — it would have been placed in the same 

 general group as the divers and grebes of the present 

 day." 



So far as I am aware, no objection to the erection 

 of a sub-class upon a purely dental basis, has been 

 offered, even upon the part of some who have not 

 usually been slow in critcising our author's conclu- 

 sions. 



Yet Prof. Marsh himself appears to be by no means 

 settled in his conviction as to the taxonomic relations 

 of the forms in question, since his "Conclusion" con- 

 tains the following qualified expression of opinion : 

 " For the present, at least, it seems advisable to regard 

 the Odontornithes as a sub-class, and to separate them 

 into three orders." 



The above intimation of a willingness to review 

 this part of the subject removes the hesitation which 

 one naturally feels in differing from the highest — and, 

 in one sense, the only — odontornithological authority, 

 and I therefore venture to offer certain considerations 

 which seem to have been overlooked hitherto. 



1. Are the other characters of the toothed birds 

 such as to warrant their separation as a sub-class? In 

 other words, can we conceive of edentulous Odon- 

 tornithes as we have Vertebrates without vertebrae, 

 and Edentates provided with teeth ? 



2. Why should the presence of teeth in certain 

 birds be accounted of more taxonomic significance 

 than the absence of the same organs in the members 

 of other classes ? The truly edentulous edentates are 

 held to form merely families or sub-orders ; the (tooth- 

 less) turtles are commonly regarded as an order of 

 reptiles ; and Prof. Marsh himself has established the 

 sub-order Pteranodontia, the " distinctive feature of 

 which as compared with the other Pterosauna, is the 

 absence of teeth." 



3. If birds with teeth had been known to us at all 

 times, or in the recent state, or in great number and 

 diversity, is it probable that, the entire group having 

 the rank of a class, we should have been led to form 

 two primary groups, the Odontornithes and the An- 

 odontornithes. 



4. How would the question appear in case unmis- 

 takable evidences of teeth are found in the embryos 

 of recent birds ? That such signs will be sometime 

 discovered can hardly be doubted, especially when 

 the embryology of the ostrich is as well known as that 

 of the common fowl. Some are even now of opinion 

 that such structures have been seen. So cautious a 

 compendium as Rolleston's Forms of Animal Life, 

 says : "dental papillae, with caps of dentine, have 

 been observed in the embryos of Psittacidae." Since, 

 however, Prof. Marsh holds (p. 13) that the "vascu- 

 lar papillae seen by St. Hilaire and others were appar- 

 ently portions of the horny beak," we may consider the 

 point unsettled. 



5 . May it not be that, in our natural surprise at the 



