10 THE AMERICAN MONTHLY [Jan. 



Studies in the Elements of the Anatomy of the Lower 



Vertebrates. 



r.Y HKN'IJY LKSI.IE O.SP.OHN. 

 IIAMLINK UMVKKsn Y. Vr. I'AI.I,, MINX. 



PART 11. 



THE TAILED AMPIIfBlAN, 



Amblystoma t'gnnuin, The Salamander. 



CONTENTS. 



1. External Anatoiuy. 9. The Uro-Genital System. 



2. The Head and Throat. 10. The Muscular System, 



3 The Braiu. 11. Fine Structure of Miisrle. 



4. The Body Cavity. 12, The Nervous .Sy.stem. 



5. The Heart. l:>. The Axial Skeleton. 



6. System. 14. The Skeleton of the Limhu. 



7. The Alimentary System. 15. The Skull. 

 H. The Lunfis. 



[This discri[ytiou is drawn directly fioiii Amblystoma 

 tigrinum, a species that is abundant in the outskirts of 

 Saint Paul, especially in the Autumn montlis during 

 damp weather. It will apply to any of the urodeles well 

 enough for the purposes of a guide; and can be used for 

 the frog, though with considerable modifications, especi- 

 ally for the skeleton of the body.] 



1. External Anatomy. — The characteristic e.xtcrnal 

 features as found in the higher vertebrates are readily 

 seen, viz: a division of the body into hcad^ neck, trunk 

 and post-abdomen\ the presence of an anterior and a pos- 

 terior limb. Examine tliese and note in each three prin- 

 cipal regions: upper, middle and Imocr which are similar 

 in all but not precisely the same. Of the front limb the 

 upper region is called the brachitini, the middle the anie- 

 brachinm, and the lower the nianus which is again divided 

 into: the carpus or wrist and the digits. The hind limb in 

 a similar manner presents: the thigh, the cms in\(\. iha pes, 

 which IS divided into the tarsus, and digits How do these 

 regions compare as to length? What differences do you 

 find between the manus and the pes? How do the limbs 

 f.ompare with those of the frog? Do you recognize the 



