EXPLANATION OF PLATE XIII. 



FIGURE 65. Autolytus cornutus, (p. 590;) an asexual individual, from which a male is 

 about to separate; dorsal view, enlarged about six diameters; A, A, A, 

 antennse of the former; C, C, C, C, two tentacles and one tentacular 

 cirrus on each side, followed by the dorsal cirri ; F, the intestine ; d, the 

 long seta? and dorsal cirri of the male. 



66. The same ; anterior part of a female, more enlarged ; the letters as before ; 

 &, the eyes; c, the eggs; /, the intestine; 3, one of the appendages of 

 the anterior region of the body ; c, the dorsal cirrus ; h, the setigerous 

 tubercle, supporting hooked sette. 



67. Diopatra cuprea, (p. 593 ;) head and anterior part of body, showing part 

 of, the branchiae ; side view. 



68. The same; ventral view, showing the mouth open and jaws thrown back. 



69. Lunibriconereis opalina, (p. 594 ;) anterior part of body ; dorsal view. 



70. The same ; lateral appendage and seta 1 . 



(Figures 65 and 66 were copied from A. Agassiz ; 67, 68, 69 were drawn from nature by J. H. Emer- 

 ton ; 70, by A. E. Verrill.) 



