270 



HARDWICKE'S SCIENCE-GOSSIP. 



acid containing only one carboxyl group " (page 1070). 

 When its younger brothers, containing several carboxyl 

 groups are born, and named according to their more 

 complex composition, the result may be imagined. 

 These are all culled from pages 1062 to 1070 of the 

 October number. I have marked others in the 

 November number, but in mercy to my readers will 

 not quote them. 



Professor Odling proposes to supply empirical 

 names instead of these, justly observing that " the 

 primaiy purpose of a name is undoubtedly to designate 

 and not to describe." In " The Gentleman's Maga- 

 zine" of October, 1880, I illustrated the result of 

 this principle of naming a thing by a description of 

 its composition, by applying it to the case of our 

 familiar Christmas-pudding, Suctofloiircggcandiedpcd- 

 raisiiispicecurrantsconglomerate, would thus be its 

 pretty little title. 



As the primary object of 99 '9 per cent, of the 

 researches which produce these violent neological 

 outbreaks is to establish the reputation of the analyst, 

 why not carry out this purpose more effectually by 

 bestowing upon these new concoctions the names of 

 their parents, with a distinctive prefix ? Thus Smith's 

 chemical first-born might be named Alpha Smith, his 

 second Beta Smith ; then Gamma, Delta, and on to 

 Omega Smith. After this Alpha A. Smith, Alpha 

 B. Smith, &c, to the end of the Roman alphabet. 

 This would supply 24 X 26 = 624 names, after 

 which numerals might be used, 625 Smith, and so on 

 to the required number of thousands. 



CHAPTERS ON FOSSIL SHARKS AND 

 RAYS. 



By Arthur Smith Woodward. 



V. 



Myliobatid^e. 



SOME of the largest and most pelagic of the living 

 Batoidei are included in this family, and fossil 

 remains of at least three genera are not uncommon in 

 the Tertiary deposits, both of this country and the 

 Continent. One of their most characteristic features, 

 and that which is of greatest interest and importance 

 to the palaeontologist, consists in the nature of the 

 dentition. The mouth is armed with a number of 

 flat crushing plates, often united firmly together by 

 sutures and varying in arrangement in the different 

 genera ; they are placed in successive transverse 

 series, and as the front rows become unfit for use, 

 they fall out of the mouth, being replaced by new 

 ones from behind. These dental plates, together with 

 specimens of the barbed spine fixed upon the tail of 

 some forms, constitute all the known fossil evidence, 

 and are met with in Eocene strata at Sheppey, 

 Bracklesham, and Barton ; in Miocene at various 

 Continental localities ; and in the Pliocene Crag of 

 Norwich. The type-genus is Myliobatis, in which the 



six-sided teeth are arranged in seven rows (fig. 1S1), 

 the median row consisting of much elongated plates, 

 and the three lateral rows on each side, of small 

 hexagonal plates. About eleven species are recorded* 

 from the London Clay, and the Bracklesham and 

 Barton beds, the most important being M. Toliapicus 

 and M. Dixon/, and associated with them are examples 

 of caudal spines. The dentition of ^Etobatis, also 

 found in the same strata, differs from that of Myliobatis 

 in consisting only of a single row of plates (fig. 182). 

 About six species of this genus have been described 

 from the English Eocenes, but the fact that the teeth 



Fig. 181.— Teeth of Myliobatis. 



Fig. 182. — Straight teeth of sEtobatis. 



Fig. 183.— Arched teeth of Mtobatis. 



of one jaw are sometimes nearly straight (fig. 1S2), 

 while those of the other are considerably arched 

 (fig. 183), renders the specific determination of de- 

 tached plates somewhat uncertain. Zygobatis (fig. 184) 

 is another form, referred to the living RJmwptera by 

 Dr. Gunther, and characterised by the disposition of 

 the dental armature in seven longitudinal rows, as in 

 Myliobatis ; here, again, the plates are six-sided, and 

 also united to form a tessellated pavement, but besides 

 the relatively great breadth of the middle series, the 

 two adjacent rows are also considerably elongated 

 in a lateral direction, and there are thus only two 



* Dixon's "Geol. and Foss. Sussex," 1st edit., pp. 197-200; 

 see also " Agassiz' " Rech. Poissons Fossiles." 



