vol.i.] Torrey. — Hydroida of the Pacific Coast. 45 



for them, or that they do not grow during any season below 

 mean low water mark. From their prevalence on floating sup- 

 ports, near the surface and hence near the oxygen supply — usually 

 a position of great advantage in harbor water, so constantly 

 fouled with sewage and other dirt — I suspeet the latter to be the 

 more probable alternative.* 



A word might be added with reference to S. F. Clark's 

 species, Tubularia elegants, collected on the piles of a wharf in 

 San Diego Bay. Clark's description would suffice for T. crocea, 

 with two exceptions: 1. There are "about thirty tentacles in the 

 proximal set" in T. elegans, while I have never seen more than 

 twenty-five by actual count in T. crocea. 2. Instead of several 

 flattened tentacular processes around the mouth of the gonophore, 

 there are four conical tubercles crowning the larger gonophores, 

 which Clark has figured. 



The first difference is of little consequence, since "about 

 thirty" might mean twenty-five. The second is more important, 

 and I would not have been led to doubt the validity of Clark's 

 species, had I not found in the University of California collection 

 several colonies of T. crocea from Coronado. In some of the 

 female gonophores, the tentacular processes are much contracted 

 and might be judged without careful observation to be conical 

 and fewer in number than they really are. Clark's material 

 was very poor, being in "the same delapidated condition" as a 

 Bimeria (?) packed with it, whose "hydranths and sporosacs 

 especially were in a very worn and mutilated state." These 

 facts make it evident that Clark's figure is rather diagrammatic 

 and that he did not have sufficiently well preserved material to 

 be certain of the tentacular processes. For these reasons I am 

 of the opinion that T. elegans will prove to be a synonym of T. 

 crocea Ag. 



Regeneration. Regeneration of pieces of the stem occur in 

 the way already known for T. mesembreanthemum . Both distal 

 and proximal sets of tentacles first appear as welts or ridges on 



* Since every colony arises from a single actinula, its position must be deter- 

 mined by the influences that control the movements of the actinula during its free 

 existence. It would be interesting to know whether these influences include any of 

 the tropisms, for instance, geotropism and chemotropism (with respect to oxygen. ) 



