GASTROTRICHA 



629 



25 (24) Seven (rarely fewer) large spines in two widely separated transverse 

 rows Chaetonolus spinulosus Stokes 1887. 



Length 0.0675 to o.oSg mm. Usually four large spines in anterior 

 row and three in posterior. Some may be suppressed (or lost?), leav- 

 ing three in front and only one in the center behind. Spines of 

 anterior row distinctly longer. Egg 0.0339 mm. long, covered on 

 one side with short hairs. The embryo escapes in thirty hours and 

 thirty hours later the young individual shows an ovarian egg in which 

 the nucleus becomes conspicuous six hours later. 



Fig. 975. Chaetonotus spinulosus m ioTsaXwK-w. X 665. (After Stokes.) 



26 (21) Spines present on head and neck much smaller than those on 



body 27 



27 (28, 29) Four transverse rows of large dorsal spines on posterior region 



of body. Also one large lateral spine on each side at caudal 

 process Chaetonotus acanthophorus Stokes 1887. 



Length 0.108 mm. Head and neck covered with short spines. 

 Large spines on body in four cross rows of five each, not alternating 

 so that they appear also as five longitudinal rows of four spines each. 

 The last lateral spine at the base of the caudal process is large and much 

 like those in the dorsal rows. Trenton, New Jersey. 



Fig. 976. Chaetonotus acanthomorphus in dorsal view. X 415. With dorsal 

 spine. X about 1165. (After Stokes.) 



28 (27, 29) One transverse row of large spines just in front of the caudal end 

 of the body Chaetonotus spinifer Stokes 1887. 



Length 0.1954 mm. Back and sides covered by 

 rounded imbricated scales, each with stout recurved 

 spine minutely furcate at tip. The four spines in a 

 single series immediately in front of the caudal process 

 are much larger and stouter than those on the rest of 

 the body. Egg ornamented with processes varying 

 in length and shape in different specimens. Stokes 

 distinguishes eggs with three separate patterns, respec- 

 tively, 0.0705, 0.0735, and o 0793 mm. long. Trenton, 

 New Jersey. 



Fig. 977. Chaetonolus spinifer. ^4, spinose scales. _ B, por- 

 tion of egg, showing trilid and quadrifid spines in profile 

 and surface aspects. Highly magnified. (After Stokes.) 



