166 



less developed median laminate process springing from the proximal margin, 

 while in others it ,is as in Hem. Michaelseni only represented by a group of 

 spinous processes. Also the form of the proximal margin of the definite aperture, 

 which according to Busk in Hem. labiata is always strongly projecting (»the 

 strong projection forwards of the oral bridge «) is subject to great variation, being 

 sometimes straight, sometimes more or less deeply sinuated and sometimes pro- 

 jecting. While the rosette-plates are as a rule membranaceous I have in the 

 form steganoporoides found a number of plates showing a greater or lesser degree 

 of calcification. 



Foraminella n. g. 



The somewhat arched frontal wall has no pores, but on each side a longi- 

 tudinal series of (1 — 5) foramina (opesiulse). A membranous opercular valve. 

 Independent avicularia without cross-bar, with an elongate mandible, on the one 

 side furnished with a wing-like expansion. Hyperstomial ooacia with a membran- 

 ous ectoooecium. Pore-chambers. 



The only representative of this genus is Monoporella lepida Hincks. As the 

 name Monoporella must be kept for the first species, referred to this genus, M. 

 nodulifera Hincks, which seems to be very different from F. lepida, I have been 

 obliged to set up a new genus for this species. 



Calpensia JuUien^, char, emend. 



The opesiular outgrowths join the lateral walls, forming a closed hollow on 

 each side. A simple, feebly chitinized operculum. Numerous pores, but no spines. 

 No ocEcia. No avicularia. The distal wall consist of a basal horizontal and a 

 frontal ascending part, the former being furnished with a narrow transverse 

 group of small uniporous rosette-plates. The distal half of each distal wall with 

 a single multiporous plate. 



This genus to which only a single species, viz. Micropora impressa Moll can 

 be referred, and which makes a transition to the following group Tiibifera, is 

 nearly related to the genus Thalamoporella, from which however, it differs in the 

 lack of spicules, ooecia and avicularia. Besides, in no Thalamoporella, both the 

 opesiular outgrowths reach the lateral walls, and only in one or two species is 

 found a simple operculum with a straight proximal margin. 



1 45, p. 78, 



