638 Jacob Parsons Schaeffer. 



ten sind." Kallius holds that seldom are all six furrows differ- 

 entiated. Mihalkovics says that "Knorpelige Muscheln sind 

 beim Menschen im embryonalen Leben stets 4 vorhanden, oft 

 auch 5." The latter, however, includes among this number the 

 concha nasalis inferior, which has not been done by the other 

 writers mentioned, since they considered the ethmoidal region 

 only. 



After an extended study of the ethmoidal region in fetuses, I 

 find that there is more or less uniformity up to the fourth month. 

 However during the latter half of fetal life there is indeed great 

 variation in the number and form of the ethmoidal conchae and 

 meatuses. Notwithstanding this I think that careful 'analyses 

 indicate a general plan more or less common to most ethmoidal 

 regions — some specimens differing here and others there from the 

 plan. Occasionally some specimens differ so markedly from this 

 general plan that they are difficult of comparison. 



Doubtless the personal equation is quite a factor in determining 

 the number of ethmoidal conchae. In many cases some of the 

 conchae are so rudimentary that one observer might not consider 

 the under-developed folds as individual conchae, yet another 

 observer would include them among the number. 



I find by careful study of the ethmoidal region in a series of 

 specimens from late fetuses that five ethmoidal conchae are not 

 uncommon, however the most superior and dorsal conchae may 

 be but faintly outlined. We occasionally find all five conchae 

 well marked (fi.g. 21). In this respect my observations agree with 

 those of Killian — he giving six as his highest number of eth- 

 moidal conchae. The apparent discrepancy in number is due to 

 the fact that he (Killian) names the agger nasi (nasoturbinal) 

 plus the processus uncinatus as his 'erste Hauptmuschel.' On 

 the other hand I do not do this, but consider his ' zweite Haupt- 

 muschel' as my concha nasalis media. I find four ethmoidal 

 conchae very frequent indeed, in fact fully 65 per cent of later 

 fetuses, according to my series of specimens, present four (fig. 26). 

 It must, however, be remembered that some of the conchae or 

 folds are extremely rudimentary, nevertheless they must be taken 

 into consideration when analyzing the ethmoidal region. Occa- 



