414 



INVEETEBEATA 



CHAP. 



If some investigator were to devote a summer to the subject and 

 to repeat Morse's observations on the living larvae, if better methods 

 of preservation were used and the celloidin - paraffin method of 

 embedding employed, as described in Chapter II., there is no doubt 

 that a flood of light vfould be throv^fn on the subject. Professor Morse 

 himself, who has deserted zoology for other fields of research, once 

 expressed to us his regret that no one had so far followed in his 

 footsteps, and he maintained that the larvae could be reared through 

 their metamorphosis without any difficulty. 



Whilst, however, awaiting the advent of a zoologist who will 



ach 



Fig. 328. — Two young TerebrcUulina septentrionalis immediately after the metamorphoses. 



(After Morse.) 



A, specimen showing six bundles of iirovisional cliaetae. B, specimen showing the origin of the 

 first tentacles, axh, adult chaetae ; h, head segment ; d.v, dorsal valve ; l.ch, larval chaetae ; m, mouth ; 

 ten, first tentacles of the lophophore ; v.v, ventral valve ; ped, peduncle. 



thoroughly clear up the subject, a few provisional conclusions may 

 be briefly indicated. Professor Morse himself entertained no doubt 

 that the Brachiopoda were an ancient offshoot from the Annelidan 

 stem, basing his conclusion on the presence of distinct segments and 

 of chaeta-sacs in the larva. 



In most Brachiopoda there is no anus at all, although there is a 

 blind and apparently functionless intestine ; but in a few archaic 

 genera, grouped together as Ecardines, an anus exists. In Lingula 

 this is situated on one side, near the origin of the peduncle — which 

 in this genus alone is muscular, — in the groove between dorsal and 

 ventral mantle-lobes. In Crania it is situated in the middle line, 

 at the posterior end of the animal, since in this genus the foot 



