Polyzoa of the St. Lawrence. 225 



MuCRONELLA, Hincks. 



Mucronella pi'celucicla, Hincks. (PI. XV. fig. 3.) 



This species was described and figured in my " Report on 

 the Polyzoa of the Queen Charlotte Islands " *. It is figured 

 again in the present paper because the St. -Lawrence speci- 

 men differs in some respects from the North Pacific, and 

 notably in the absence of the peculiar projections, placed one 

 on each side of the cell at the base of the raised peristome. 

 These have much the appearance of avicularia, but are not 

 really such. The diminutive zooecium in the present figure 

 is probably one of those which lie about the primary cell ; 

 but all the cells are smaller in the St.-Lawrence than in the 

 Pacific specimen. In the Queen-Charlotte Report I ventured 

 to conjecture that the new forms described in it would pro- 

 bably not be to any great extent arctic. There can be little 

 doubt, however, that Mucronella prcelucida at least has followed 

 the usual course of migration from the extreme north along 

 both the Atlantic and Pacific coasts of America. 



Smittia, Hincks. 



Smittia Landshorovii, Johnston, form porifera^ Smitt. 

 (PI. XIV. fig. 2.) 



The only form referable to the above species which has 

 yet occurred to me amongst the St.-Lawrence dredgings 

 would rank under Smitt's Escharella porifera. This must, 

 I think, be accounted a "form" of S. Landshorovii ] the 

 differences between them are hardly of sufficient moment to 

 warrant their separation. They may be briefly summed up. 

 In 8. porifera the zooecia are ovate or (frequently) rhombic, 

 very thickly punctured over the entire surface, and of a dull 

 white colour ; the peristome is less elevated than in the nor- 

 mal S. Landshorovii^ the aviculariura is larger and rather 

 more elongate, and stands out very prominently below the 

 inferior margin, so as to have a rostriform appearance. Tlie 

 central denticle is sometimes wanting, and when present is 

 less conspicuous than in the ordinary form, owing to the larger 

 size and greater prominence of the avicularium ; it is some- 

 times small and pointed. The orifice is subcircular, whilst 

 in the latter it is more correctly described as " rotundato- 



* Ann. & Mag. Nat. Hist. ser. 5, vol. xiii. pi. iv. Reprinted for the 

 Geol. & Nat. Hist. Survey of Canada, 1881, p. 'IQ (sep.), pi. iv. fig. 1. 



