ON RECENT POLYZOA. 527 
Genus Dimetopia, Busk, ‘Brit. Mus. Cat.’ 
»  Scruparia (pars), Hincks (not Smitt). 
» ? Brettia, Dyster. 
»  Huxleya, Dyster. 
But only species of two genera are described in the ‘ Challenger Report.’ 
Genus 22. Gemellaria, Savigny. 
‘Zoarium erect, phytoid. Zocecia joined back to back; the cells 
composing the pairs rising one from the top of the other, all the pairs 
facing the same way. Aperture large, on the front of the cell, slightly 
1. Gemellaria loricata, Linw., Sys. Ed. 10-815; Hincks, ‘ Brit. Mar. 
; Pol.,’ p. 18, pl. i. figs. 1-4. 
m2(?). Willisii, Dawson, coasts of Nova Scotia. This latter 
form differs from G. loricata ‘in its narrower and 
less inflated cells and longer apertures, and in its 
more dense habit of growth.’ I believe with Mr. 
Hincks that the species ‘ presents only the character 
of a variety,’ and he places it as a synonym of 
G. loricata. 
Genus 23. Didymia, Busk. 
Didymia, Busk, ‘ Voy. of Rattlesnake,’ ‘ Brit. Mus. Cat.’ 
_ *Zocecia joined side by side, all facing the same way. At a bifurcation 
each zocecium of the primary pair giving off a secondary pair. Frontal 
area almost entirely membranous. Ocecia on a third intermediate zocecium 
at a bifurcation.’— Busk, ‘Chal. Rep.’ p. 47. 
Didymia simplex, Busk, ‘Chal. Rep.’ p. 47. Id., ‘Brit. Mus. Cat.,’ 
Macgil., Wyville Thom. 
Genus 24. Dimetopia, Busk. 
‘ Brit. Mus. Cat.,’ ‘ Voy. of Rattlesnake,’ Macgil. 
‘Zocecia in pairs, apposed back to back ; infundibuliform, witha large 
orifice, each pair facing in a direction at right angles to that of the 
next; at a bifurcation each of the separate zocecia gives of a secondary 
 pair.’—Busk, ‘ Chal. Rep.’ 
1. Dimetopia cornuta, Busk, ‘Chal. Rep.’ p, 47. 
2. . spicata, Busk. 
i 
Genus 25. Scruparia, Hincks. 
_- * Joarium erect. Branches given off from the back of a cell, and 
_ facing in the opposite direction. Zocecia sub-calcareous, rising one from 
_ the other, so as to form a single series, or placed back to back. Aperture 
small, unarmed, slightly oblique, terminal. Ovicelligerous cells small, 
and imperfectly developed, placed back to back with the ordinary cells. 
Ocecia terminal. No avicularia or vibracula.’—Brit. Mar. Pol. p. 21. 
Scruparia clavata, Hincks, ‘ Brit. Mar, Pol.’ p. 24. 
‘Quart. Jour. Mic. Soe.’ pl. xvii. figs. 5-8. 
