Analytical Sy^iopsls of the Order of Squali. 389 



Gen. Scymnus Cuv., Lsemargus MIL, Ecliinorhinus Bl. 

 Familia 17. Squatinoidei = Squatinini Bp. = Squatin£E S\vns.==Squa- 

 tinidae Riclids. 

 Gen. Squatina Duin., Radamas Miinst., Xeracanthua Beyrich. 

 Familia 18. Pristiophoroidei. 

 Gen. Pristiophorus MH. 



Gen. famil. dub. fossil : Chilodus Gieb., Hemipristis Ag., Gom- 

 phodus Reuss, Ancistrodon Debey. 

 At the end of the order are inserted the generic names of many ich- 

 thyodorulites.' 



Ill this classification, the extinct genera, as well as the recent 

 ones, are included. The former are indicated by the names 

 printed in italics. As they have been mostly founded only on 

 fragments, and especially the teeth, their proper place is often 

 doubtful, as there is no certain correlation between the modifi- 

 cations of structure and dentition, as is the case with the mam- 

 mals. As will be apparent from the study of the order, nearly 

 or quite the same dentition is observable in very difl'erent fami- 

 lies, while very decided differences of dentition may occur in 

 one group whose aggregation of characters indicates it to be a 

 natural family, as such is now generally understood by selacho-. 

 logists. The classification of Dr. Bleeker is, however, at least 

 valuable, as being suggestive of their relations, and is, therefore, 

 transcribed for the benefit of those who may not have access to 

 the original work. The families adopted, as well as the order 

 followed, are mostly similar to the classification of Richard- 

 son ; the principal difference is the sequence of the family of 

 Zygsenoidei after the Carcharoidei, in which respect it more 

 resembles Miiller and Henle's. The " tribes" and " sections" of 

 Dr. Bleeker do not appear to indicate any modifications of 

 structure of paramount importance, and the section of " Aprok- 

 pterides" is scarcaly natural. There can hardly be a doubt 

 that the Squatinoidei are the most aberrant as to positive cha- 

 racters, of any of the sharks, and that if a subdivision is made, 

 those fishes are entitled to the rank. 



