1884.] Aspects of the Body in Vertebrates and Arthropods. 855 
Pyrgula nevadensis varies in size within rather wide limits. 
Twenty-five specimens, taken at random, present the following 
averages: Length 4.83™™"' breadth 2.65™™- These proportions are 
best shown graphically, as are also the extremes of variation, by 
the accompanying plate, xxv, in which 2™™ is adopted as the 
origin of the codrdinates. Each small square represent a .10"™ 
The dot underlined represents the average of the specimens . 
measured. At some future time more complete notes on this 
species, and on those inhabiting the salt springs and lakes of the 
Great Basin, from a biological standpoint, will be presented the 
readers of the NATURALIST. 
to: 
ASPECTS OF THE BODY IN VERTEBRATES AND 
ARTHROPODS. 
BY A. S. PACKARD. 
NDER the title “ Aspects of the Body in Vertebrates and 
Invertebrates” (London, 1883), the venerable and distin- 
guished English anatomist and palzontologist, Professor Sir 
Richard Owen, renews in a vigorous way the old discussion 
originally begun by Geoffroy St. Hilaire. The view in question 
1s tersely presented in St. Hilaire’s answer to Dugés, quoted by 
Professor Owen, when he replied by reference to “ Fig. 2 de la 
septième planche: La se trouve effectivement représenté un 
homard couché sur le dos et montrant distinctivement ses vis- 
céres dans la position où le sont les viscères des mamiferes 
Placés sur le ventre.” This view was combatted by Cuvier, and 
in this respect he has been followed by Gegenbaur. 
In his able essay Professor Owen places himself on the side of 
St. Hilaire, and the special point in vertebrate anatomy which he 
brings forward to support this opinion is the homology of the 
conario-hypophysial tract, which he regards as “the modified 
homologue of the mouth and gullet of invertebrates ;# and at 
the end of chapter I he concludes that “ the surfaces or aspects 
of the body which are truly homologous in the snake and cater- 
pillar are the meural and the hemal, not the dorsal and the 
ventral,” 
In his second chapter, entitled “Cerebral homologies in verte- 
brates and invertebrates,” Professor Owen quotes our statement’ 
"Second report U. S. Entomological Commission. Chapter XI. The brain of the 
Locust, p, 224. 1880 
