124 Mr. G. E. Dobson on a new Species of 



drawing was taken, during tlie resting state of tlae animal, from 

 above, from the oral surface. 



Fig. 8. Mother-generation (B) from the side. The animal was drawn 

 while irritated by the pressure of the glass cover. The eight 

 superior and eight inferior radial tentacles are bent upwards and 

 conceal the proboscis with the mouth, while the four superior 

 (lateral) and the four inferior short, clavate feelers project 

 below. The endoderm of the central and two lateral gastral 

 cavities is perceptible through the transparent ectoderm, as also 

 the axial cavities in the tentacles. x8. (Compare tigs. 6, 11, 

 12, 13, and 15). 



Fig. 9, One of the paired daughter-forms (B^) produced by the halving 

 of the mother, shown in figs. 7 and 8. In a state of rest from 

 the oral side. Eight radial tentacles and four feelers, two of 

 which are longer than the others. X 10. 



Fig. 10. The same form from the side, showing the insertions of the ten- 

 tacles, with the continuations of the gastral spaces. The pro- 

 boscis with the mouth is below; above are the four feelers, 

 laterally the eight radial tentacles. X 10. 



Fig. 11. The same form from the side, in a state of rest, standing upon 

 all the twelve tentacles. The body is lifted up and the proboscis 

 directed upwards. X 10. 



Fig. 12. First form (B") of the grandchild-generation, with four long 

 radial tentacles and two feelers. This form has been produced 

 from the lower half of the daughter B^, shown in tig. 9. X 12. 



Fig. 13. Second form (B'-' h) of the grandchild-generation, produced from 

 the upper half of the same daughter-form (fig. 9), with shorter 

 tentacles than the form B^ (tig. 12). While being drawn the 

 four radial tentacles, directed upwards, were slightly re- 

 tracted *. 



Fig. 14. Second mother-generation (a B) with the tentacles thrown off", 

 their places of origin being indicated by the lateral and basal 

 tubercles of new tentacles in course of formation, x 10. 



Fig. 15. The same specimen drawn thirty-six hours later, with twelve 

 newly-formed tentacles on the aboral side, and twelve tubercles 

 of increased size, which in the sequel will grow into lateral radial 

 tentacles and feelers, x 18. 



XIV. — Description of a new Species q/ Vesperugo //-om North 

 America. By G. E. DoBSON, M.A., F.R.S. 



Vesperugo Merriami^ n. sp. 



Smaller than Vesperugo pijnstrellus, with which it agrees in 

 general subgeneric characters ; ears shorter than the head, 

 shaped somewhat like those of that species, but the outer 

 margin of the conch is much less deeply emarginated, and the 

 projecting part of the lower half of the same margin is folded 

 backwards; tragus broad, the outer side of its upper half 



* Similar specimens were observed by Owsiannikow and Grimm, and 

 figured by them with abnormally extended and already somewhat mace- 

 rated tentacles. 



