274 



Genera: 



The aperture surrounded by spines, with a concave poster and 

 with no sinus; an avicularium proxiniallj' to tlie aperture; distal wall 



willi uniporous rosette-plates; ooccia jiresent Scwiynijella n. g. 



Catenaria d'Orbigny. 

 (S. Lafonti Audouin^) 

 The projecting aperture not surrounded by spines, Init with a 

 rounded sinus; distal wall with niultiporous rosette-plates; avicularium 



and oa>ciutn wanting H(tlysisis Norman -. 



(//. diapbana Busk^.) 



Time has not allowed of my entering into a close examination of the two 

 species, which I think show sufficiently great conformity to belong to the new 

 family that I have been obliged to found for them. It is possible that C(iteiuiri(t<^ 

 uttemiata Busk^ may also be entered in this family. With regard to the cpiestion 

 of their descent, they seem to me lo show relationship particularly to liicellariidae, 

 and of characters that favour this opinion I may mention the slight calcification, 

 the long slender form of the zomcia, the form of colony and the structure of the 

 oo'cia. Also the freely projecting avicularium in S. Lafonti may be taken as evi- 

 dence of such a relationship. While I have found a covering membrane on the 

 frontal surface in C. diuplmna, I have not succeeded in finding one in S. Lafonti, 

 in which however according to the examination made by Calvet it must be 

 supposed to be present. — The two just-mentioned sj)ccies have by Busk* and 

 later authors been called Alijsidiuni Lafonti And. and Catenaria diaphana Busk. 

 But it has been necessary to make two new generic names, as tlie name Ali/si- 

 dium must be kept for A. j)arasiticnm Busk, and Catenaria Contei And. is the ty|)e 

 of a genus belonging to the family Catenariidae (see pug. 2i;{, note). 



Family Hippothoidae. 

 Diazeuxidae JuUien. 



The zoo'cia, which have no covering membrane, are generally thin-walled, 

 glistening, more or less distinctly longitudinally or transversely striated, and the 

 calcification, which constantly increases simultaneously with the growth, lakes 

 place in transverse belts, of which a greater or smaller number often terminate 

 in thin protruding margins, which .surround the frontal surface like a belt. 



' ns, pi. l.t, ngs. 2,.— 2,7. -' 84 a, p. 29r>. ' 8, p. 14. ' 2, pp. l.'l — J4. 



