The Microscope. 41 



16. Chcetonotus octonarius, sp. nov. — Plate I, fig. 4. 

 This is a small and active form, easily recognizable by the 

 arrangement of the recurved dorsal spines. These are unequally 

 furcate, and placed in two lateral longitudinal rows of three thorns 

 each, with one central anterior and one central posterior spine. The 

 species appears to be uncommon. I have met with but a single spec- 

 imen which I neglected to measure. It needs further study. 



17. CJuetonotus sjjino.'^ulus. sp. nov. — Plate I, figs. 2 and 3. 



Body ^4 jT inch in length, the cnticular surface granularly rough, 

 and the back usually bearing seven unequally furcate spines in two 

 transverse rows, four spines in the anterior series, three in the pos- 

 terior. Occasionally the lateral thorns in the posterior row are sup- 

 pressed, and, in some individuals, the front series contains but three 

 spines. The lateral margins of the body are bordered by short, con- 

 ical setre, these being constant in all the specimens observed. 



The egg is -^-\j^ inch long, and the ends and one side are 

 hispid with short hairs (fig. 3). The embryo escapes in about thirty 

 hours after the egg has been deposited, and in about thirty hours 

 later the young Chaetonotus begins to show that the development of 

 an ovarian egg is beginning, and in six hours later the nucleus 

 becomes conspiciious. The extrusion of the egg here referred to was 

 witnessed, and the parent subsequently died. After the escape of 

 the embryo, which I also witnessed, it was hoped that the ovum 

 forming in the ovary of the young animal might proceed to full 

 development and give some inkling as to the method of fertilization. 

 There was but this one Chaetonotus in the life-slide, and I had an 

 opportunity not likely to be soon repeated, but before the back 

 began to be arched above the developing ovum, the animal died. 



18. Chcetonotus longispinosus, sp. nov.^ — Plate I, figs. 8 and 9. 



The unequally furcate spines vary in number from four to eight, 

 the latter being the iTsual complement. They are nearly one-half 

 the length of the entire animal, and rise from the central region of 

 the dorsum in two transverse rows, commonly of four spines each, 

 and arch upward and backward (fig. 8) to near or beyond the ends 

 of the caudal branches, those forming the most posterior series being 

 the longest. In front of the anterior the surface is setose with a 

 few recurved bristles, as shown in fig. 9, and the body-margins are 

 bordered by a fringe of coarse, stiff seine. The dorsal spines are 

 always in two rows, but the number varies from four in each to three 

 in one and five in the other. The body is ^^j inch in length. 

 The egg was not observed. 



