250 BULLETIN OF THE 
appears to be, then, a structure which we may look upon as a rudimentary 
hydrotheca ; moreover, this view receives support from the position of these 
processes, that is, at the bases of the hydrotheca-bearing portions of the colony, 
with the contents of the hydrothece in immediate connection with that of 
these basal processes. 
After the very valuable suggestions of Professor Allman * on this point it is 
not difficult to conceive that the pinnae of N. grandis may at one time have 
borne only oval processes of a large and peculiar type, much like the oval basal 
processes now found on the bases of the pinnis, and that these have been grad- 
ually developed into true hydrotheec. The development of the upper corners 
of the cauline nematophores indicate how the supra-calycine nematophores 
may hove been produced. 
The contents of one of the mesial nematophores with its extruded protoplas- 
mic processes has been so well preserved that I have been able to get an accu- 
rate camera-lucida sketch of it (Plate V., Fig. 35). It has the same structure 
apparently as those figured by G. O. Sars t in his Lafoéina tenuis. 
* Gymnoblastic Hydroids, Ray Society, p. 176 et seq. Hydroids of the Gulf 
Stream, in Mem. Mus. Comp. Zoól. Vol. V. No 2, p. 51. 
+ Bidrag til Kundskaben om Norges Hydroider, Af G. O. Sars, Tab. V. Figs. 4, 5. 
‘AMBRIDGE, January 10, 1879. 
