210 THE APODID^: PART 11 



are the earliest known Crustacean forms. A special 

 interest therefore attaches to our endeavour to prove 

 that they were nearly related to the Apodidae. Start- 

 ing from a purely morphological and anatomical 

 standpoint, we endeavoured to show that Apus was a 

 modified Annelid, and, therefore, a primitive Crus- 

 tacean. Our finding that the Nauplius, or the earliest 

 known larval stage in Crustacea, is but a young Apus, 

 went far to show that our reasoning was correct. If 

 now we can further show that the earliest known 

 Crustaceans are easily connected with the Apodidae 

 as related forms, it seems to us that our case is 

 established. Such concurrent testimony from deve- 

 lopmental history and from palaeontology is almost 

 without parallel. 



The relationship of the Apodidae and the Trilobites 

 has already been assumed by the earlier zoologists. 

 Burmeister, 1 indeed, tried to reconstruct the Trilo- 

 bites on this assumption, and attributed to them the 

 typical Phyllopodan limbs, and described them as 

 swimming about in the palaeozoic seas. Although 

 Burmeister's reconstruction was not correct, yet his 

 assumption of a relationship between the two was 

 justified. The fact that the Apoclidae have rowing 

 limbs does not in any way oblige us to assume that 

 if the Trilobites were related to the Apodidae they 

 must have had similar limbs. As a matter of fact we 



1 Cf. " Die Organization der Trilobiten aus ihren lebenden Verwand- 

 ten entwickelt,'' and further the historical review given by Walcott in 

 his paper, "The Trilobite. Old and new evidence relating to its 

 organisation." 



