194 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



witii a broad, vsliallow, median sinus, and small, lateral, opercular denticles. 

 Ocecia large, prominent, globose, the surface rough with sharp gran- 

 ules, and perforated by small, incouKspicuous pores. Avicularia scarce, 

 often absent, when present lateral, opposite the side of the aperture, 

 broad, obtusely rounded, the point directed toward the zooecial a])er- 

 ture. Color, when dry, i-eddish brown. 



Vineyard Sound and Long Island Sound, 8 to 12 fathoms, common. 



The species here described has a close resemblance to both S.porifera 

 and 8. Candida, and when the avicularia and ocecia are wanting it will 

 not be easy to distinguish them. The resemblance to S. cmidida is 

 particularly close, and extends even to the ocecia, but these are rougher 

 and less porous in E.porosa. The situation and form of the avicularium 

 are, however, the best diagnostic characters. 



This species is closelj^ related to E. sanguinea (l^ormau) of Europe. 

 It also has a general resemblance to E.pertnsa (Esper), as described by 

 Smitt; but there appears to be great confusion in regard to the identifi- 

 cation of the latter, and doubtless several sj^ecies have beeu confounded 

 under that name. Hincks refers pertusa to Lepralia. American writers 

 have referred several distinct species to pertusa, and I am not sure that 

 the genuine pertusa inhabits our coast. The species thus named by 

 Dawson, on examination of specimens kindly furnished by him, proves 

 to be Smittia porifera. Probably ^S*. Candida has also been identified as 

 pertusa by some writers. 



The generic relations of the species, well described and figured by 

 Smitt as Escharella Jaeotini (Aud.), has been variously determined. 

 In Gray's system, it appears to have been united with one of the forms 

 of Escharoides coccinea, under the name of variolosa, and referred to 

 Escharella: Smitt placed it under Escharella in a special subdivision. 

 It seems to me, however, to have more definite relations to the genus 

 Discopora, as defined by Smitt, and more particularly to that subdivision 

 of Discopora which includes D.pavonella, D. appensa, etc., characterized 

 by having lateral avicularia, and with a median denticle at the proximal 

 edge of the primary zooecial aperture, and to which the name Mucronella, 

 given by Hincks to the group called Discopora by Smitt, may be prop- 

 erly restricted. 



We may subdivide Discopora into three natural groups, easily de- 

 fined, as folloAvs : 



Discopora Lamarck {parn) restricted by Edw. {mon Fleming; non Gray). 



Dificopora {pars) Smitt, Skandiuaviens Hafs-Bryozoer, p. 25, 1868. rrdmiceJIaria 

 (pars) Hincks. 



The type of this genus, as restricted by Edwards, was D. verrucosa. 

 Lam. {non Esper). As shown by Edwards, this species is very distinct 

 from Esper's species, and is closely allied to the well-known D. Skenei of 

 the North Atlantic. Gray was, however, misled by the (piotation of 

 Esper's name in the synonymy, aud erroneously took Esper's species as 



