IX 



MOLLUSCA 



303 



succeed in keeping his larvae alive for more than a week. Kecently, 

 however, the larvae of Patella vulgata have been reared through their 



mch 



m 



m. 



ttr 



FIG. 238. Frontal section of a veliger larva of Patella coerulea in order to show the 

 mesodermic bands. (After Patten.) 



op, apical plate; m.b, mesodermic band ; m.ch, mesenchyme cells budded off from the front ends 

 of the mesodermic bands ; st, stomach ; t.tr, telotroch ; V, velum. 



-v 



FIG. 239. Frontal section through the pretrochal region of an old veliger larva of 



Patella coerulea. (After Patten.) 

 Letters as in previous figure, c.g, rudiment of cerebral ganglion. 



entire metamorphosis, until they assume the adult form. This result 

 has been accomplished in Plymouth, using Nitschia as food. The field 

 is therefore open for a renewal and revision of Patten's work. 



