104 PLANAEIA. 



power could discern two pair of eyes in each, possibly the rudiments of 

 the four clusters belonging to full-grown animals, fig. 25. When with- 

 drawn from the dark, the young Planarise rose in great numbers towards 

 the surface of the water, congregating on the side next the light and, 

 as mere atoms they were just visible. 



Without equal regularity to the cells of a honeycomb, the vacant 

 spawn bore much resemblance to them, fig. 26. 



The Plnnaria flexilis lives in society, occupying the lower side of 

 stones, the crevices of loose shelving rocks, or the cavities of shells, and 

 sometimes sinking entirely amidst mud. It must be considered littoral, 

 being found rather lower than half tide on a soft muddy bottom. 



The body is extremely thin, and lies close to the substances prefer- 

 red, from which it may be carefully washed off with a feather while kept 

 under water ; or by vitiating the surrounding element, it is forced from 

 its haunts to seek a purer medium, and ascending to the surface, it often 

 lies there supine. 



PLATE XIV. 



FIG. 17. Planaria flexilis, back. 

 18. Belly. 



J9. Anterior surface, shewing the site and appearance of the specks, 

 enlarged. 



20. Patch of spawn. 



21. Another. 



22. Portion of spawn, enlarged. 



, 23. Portion of spawn, farther advanced. 



24. Young Planaria, from the spawn. 



25. Young Planaria from the spawn, with two pair of eyes. 



26. Empty capsules left by the young, enlarged. 



</. PLANARIA MACULATA (ATOMATA ?). Plate XIV. figs. 27, 28, 29, 30, 



31, 32. 



The preceding three species of Planarice can be satisfactorily recog- 

 nised as quite distinct. But the tribe is numerous, and the distinguish- 



