New York; and Woods Hole, Massachusetts, during 1898-1908. He concludes 

 that so far as his statistical method reveals, it is extremely doubtful whether 

 or not Uro salpinx, such as those inadvertently transported from Statea Island 

 to San Francisco Bay, exhibit greater variability of this ratio when introduced 

 to new habitats. He notes that since a charge in variability accompanies drills 

 duung growth it is practically impossible to collect homologous lots of individuals 

 on which environmental modification may be accurately determined . In spite of 

 these difficulties he reports that drills from different native habitats vary widely 

 enough from each other to be easily distinguished , In particular he observed that 

 drills from localities more exposed to the beat of the waves show greater varia- 

 bility than those from more protected places; and that drills in dense populations 

 express less variability than those in sparse populations. 



At least two, and possibly three, subspecies of U. cinerea are known to 

 occur . Two are quite distinct, the small widely distributed form described as the 

 typical U. cinerea, and a giant form, U. cinerea var . follyensis (Baker, 1951) 

 from the eastern shore of Maryland and Virginia. The maximum height of U. c„ 

 follyensis collected by Henderson and Bartsch (1915) measured 51.5 mm., by 

 Baker (1951), 51.2 mm., and by Galtsoff et al. (1937), 61 mm. (Table 7). Owen 

 (1947) in a comparative cytological study of spermatogenesis in the male gonads 

 of these two subspecies shows that the diploid chromosome number (32) is constant 

 in both, but noticed that in all cases during Anaphase I of the typical U_. cinerea 

 one chromosome lags behind the others forming a distinct chromosomal bridge. 

 This chromosomal behavior characteristic is not present in U. _c_. follyensis . 

 Owen concludes that Henderson and Bartsch (1915) were correct in recognizing two 

 separate races in the species U. cinerea . 



Abbott (1954) suggests that Urosalpinx perrugata Conrad from the west 

 coast of Florida, which is similar to U. cinerea, may be another subspecies of 

 U. cinerea . 



RELATION TO OTHER ANIMALS 

 Cannibalism 



Some cannibalism occurs among LJ. cinerea of all ages in the presence of 

 other food both in the field and in confinement. Pope (1910-11) reports that in one 

 observation 100 newly hatched drills hatched in captivity were reduced to 36 . T. C. 

 Nelson (1922) doubts that such extreme cannibalism occurs in nature, since drills 

 do not all hatch simultaneously and tend to scatter. Stauber (1943) also detected 

 cannibalism among recently hatched drills ir aquaria, but an amount less than the 

 extremes reported by Pope. Pope (1910 11), Ha skin (1935), Galtsoff et al. (1937), 

 Stauber (1943), and F. B. Flower (1954, New Jersey Oyster Research Laboratory) 

 report cannibalism among adult drills in both the laboratory and in the field. 



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