332 GEOLOGICAL SURVEY OF THE TEREITOEIES. 



■wide as two-thirds its length. The outer angle or elbow varies greatly, 

 in some individuals not being noticeably produced, and with the outer 

 edge nearly straight, while in others the angle is remarkably produced 

 and the outer edge is much excavated. In one specimen, 7"'° in length, 

 the claspers are one-half as wide as in another, but with the elbow still 

 produced. In another male, 7™"' in length, selected from fifty more or 

 less normal individuals, the elbow is enormously produced, and the 

 claspers are small, long, narrow, and acute. In sixty other males the 

 elbow is a good deal produced, while the claspers are broad and triangu- 

 lar. These specimens were collected at Lake Point from the wharf, July 

 26, 1875, the temi^erature of the water under the wharf in the shade 

 being 73° F. The females bore about 23-24 eggs in their ovisacs. 



Sixty red-colored males from a hot, shallow brine pool at Farming- 

 ton, late in July, the temperature of the water ijrobably not less than 

 80° Fahr., were examined. Of these, one male, 5.5™'" in length, had 

 claspers which were even smaller and narrower than in a smaller indi- 

 vidual, 4.5™™ in length, showing an unequal degree of growth, being 

 perhaps an example of retarded development of a secondarj'^ sexual 

 character. A stronger example is seen m two individuals of the same 

 length (5.5'™") ; one was very immature, the head being smaller than in 

 the other, the claspers unusually small and narrow, the genital append- 

 ages smaller, and the caudal appendages one-half as long as in the 

 other; in the second examjile the head is large and the claspers fully 

 three times as broad as those of the first individual, being three-quar- 

 ters as broad as the si)ace between the eyes, while the caudal append- 

 ages were twice as long as thick, longer than those of A. gracilis, as 

 figured by Verrill. This difference in two specimens so neai-lj^ of a size 

 shows that the sexual characters are suddenly acquired. ISTo young 

 were observed less than 3"'™ long. 



Identity of A. fertilis, A. gracilis, and A. monica. — On comparing 30 

 males of J,, gracilis fromjSTew Haven the claspers in small specimens look 

 like Verrill's figure of those of A. gracilis; in large specimens like that 

 of his figure of A. monica, the claspers increase in width with age. In 

 two specimens of the same size and probably age, one has very narrow 

 claspers, as in Verrill's figure of gracilis, in another the claspers are 

 broader than in his figure of A. fertilis. In half-grown males the claspers 

 are narrow, as in Verrill's figure of A. gracilis. The forms of the caudal 

 appendages vary with age. 



On comparing a few days after, to be sure that I had made no mis- 

 take, 200 males of A. fertilis with males of A. gracilis, I could find abso- 

 lutely no essential specific or varietal differences between these so-called 

 Sj)ecies. 



On examining 45 females of A. gracilis from JS'ew Haven, and com- 

 paring them with a number of Salt Lake females, no differences could 

 be observed. Comparing with care a large female from Utah (Great 

 Salt Lake) with one from JSTew Haven of the same size, there was also- 

 the same proportion of parts. The ej'es were of the same size, the eye 

 stalks of the same length; the first and second, the latter especially, 

 had the same proportion. The feet and endites were the same, and 

 the length of abdomen the same, though this region A'aries, as it 

 irregularly contracts in alcohol. The egg-sacs in the New Haven ex- 

 ample are a little longer and with a more acute lateral angle than in 

 Utah examples, but this dejjeuds on age, and these differences disa])pear 

 in those which are of the same size and degree of sexual maturity, and 

 in which the eggs are similarly developed. The caudal appendages in 

 the Salt Lake example (which was 12.5™'" in length) are nearly but 



