NOtES ON EMBRYOLOGY AND CLASSIFICATION. 



44^ 



Clats. 



II. Spirobran- 

 CHiA (Brachio- 

 poda) . 



III. Lamelli- 



BRANCHIA 



Order. 



1. Ecardines 



2. Testicardines 

 '1. Asiphonia 



2. Siphonata 



Examples. 

 Discina. 

 Lingula. 

 Tereiratula. 

 Spirifer. 

 Area. 

 Unio. 

 Venus. 

 Teredo. 



Classes of the Gephyr^a. 



I. ECHIURID^. 



II. PRIAPULID.E 



III. SirUNCULID^ 



IV. Phoronid^ 



r Eehiurus. 

 \Bonellia. 

 j Priap?ilus. 



y^Halicryptus. 



{Sipunculus. 

 Aspidosiphon. 

 Phoronis. 



I. Nematoidea 



Subdivisions of the Nematoidea. 



1. Ascaridse 



2. Strongylidse 



3. Trichinidse 



4. Filaridae 



' 5. Mermithidse 



6. Gordiidse 



7. Anguillulidse 



8. Enoplidae 



9. Chsetosomidse 



(Ascaris. 

 Oxyuris. 

 f Strongylus. 

 \ Cucullanus. 

 r Trichocephalus. 

 \Tric/dna. 

 J Bracunculus. 

 \Spiroptera. 

 f Mermis. 

 \Sp}i(2rularia. 

 Gordms. 



{y Tylenchus. 

 \Rkabditis, 

 r Dorylaimus. 

 \Unckelidium, 

 Chatosoma. 

 Rhabdogaster. 



