PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 195 



the type of Discopora. Hincks attributed the name to rieming, who 

 used it in a diflereut sense, and, apparently overlooking the fact that the 

 name originated with Lamarck, rejected it for the original group. 



Discopora, as I propose to restrict it, is characterized by having both 

 median and lateral avicularia, with the former (or both) often raised on a 

 prominence in front of the zooecial aperture. 1). SJienei, with its Lepra- 

 liau form described as L. crassispina by Stimpson, is the only known 

 New England species. 



Escharoides Edw., in Lam., 1835; Gray (restr.), 1848, {non Sinitt). 

 Mucronella {pars) Hincks, .1879. 

 Type E. coccinea (Abildg.), as defined by Siuitt,= £. I'eachii (Johnston). 



This group includes those species of Discoporidce having a i)rominent 

 median denticle, but without avictdaria. The zooecial apertitre is usually 

 somewhat raised, and is often armed with marginal spines. As E. 

 coccinea was one of the species originally included by Milne Edwards, 

 Gray's restriction was correctly made, and should be adojited. 



The typical species, with several varieties, abounds on our coast. 



Mucronella Hincks (restricted), Ann. &, Mag., iii, p. 1(J2, 1879. , 



Discopora {pars) Smitt, Skandinaviens Hafs-Bryozoer, p. 25, 1868. 



Characterized by having lateral avictilaria on one or both sides of the 

 zooecial aperture, but without the median avicularium. Median denti- 

 cle of various forms, often small. Apertures armed or unarmed with 

 spines. Growth various, most often encrusting, foliaceous, or lichen- 

 like, sometimes forming thick crusts composed of many layers. Our 

 species are as follows : 



Mucronella appe/nsa (Hassal) Verrill. 



Mucronella pavonella (Alder) Hincks. 



Mucronella nitida Verrill = Discopora nitida V., 1875. 



Mucronella Jacotini (Aitd.) Y. = EscJiarelJa Jacotini Smitt. 



Mucronella scabra (Fabr.) V. = Discopora scahra Smitt. 



M. scabra, var. labiata (Stimp.) = Lepralia labiata Stimp. 



Mucronella ovafa (Smitt) V. = D. scabra, var. ovata Smitt. 



Mucronella nitida Verrill. 



Discopora nitida Verrill, Amer. Journ. Sci., ix, p. 415, pi. vii, fig. 3, 1875. 



This species is very abundant in Vineyard Sound and Long Island 

 Sound. Although it is an encrusting species, when young often forming 

 small, thin, radiating patches, when old it forms thick, irregidar, cellidar 

 crusts, composed of uuruerous layers of cells. Some of these finally 

 become large, subglobiilar masses, with an uneven surface, sometimes 

 two inches or more in diameter. The color, when recently dried, is 

 usually l)right greenisli yellow, sometimes brownish. The younger cells 

 have the walls of both oojcia and zooecia uniformly perforated; when 

 older, the bounding walls become raised ; a marginal row of consjjicuous 

 pores remains, while those over tlie front mostly disappear, or are 

 obscured by granules ; the pores of the globose ooBcia also mostly dis- 



