265 



membranous porlion, which is covered by two pentagonal, hollow spines, that 

 meet in a suture. Hetween their opercular margin and the hinge-teeth there is a 

 small sinus, and their I'orm is subject to some variation so that the suture be- 

 tween Ihem may be sometimes shorter, sometimes longer. At an earlier stage 

 these sjjines are not yet present, and the operculum (hg. .S b) at this lime 

 is proximally surrounded by a calcareous belt, se|)arated by a yellowish, glisten- 

 ing margin from the rest of the calcareous wall. A resorption of the calcareous 

 mass proximally to the operculum soon commences however, and the two sjjines 

 gradually dcvelo[) and cover the decalcified porlion. Such a [)rocess does not 

 seem to take place in E. episcopalis. 



The ooecia are high, strongly arched, almost ovil'orm, and the ectoon'cium 

 has on either side of the central line a large, triangularly rounded fenestra, hi- 

 side the narrow central belt there is a longitudinal ridge joining the endooo'cinni. 

 The ooecia-bearing zocecia have no distinct hinge-teeth and contrary to the case 

 in E. episcoj)(ilis there is but one pair of spines proximally to the operculum. 



Avicularia. On the examined fragment a single, independent, elongated and 

 lyre-shaped avicularium was found, the wholly calcified subopercular area of 

 which showed a distinct sutural line along the centre, while its opercular area 

 was provided with a strongly developed cryptocyst perforated by an oblong open- 

 ing. The mandil)le has at its proximal part two small, pointed lateral processes. 



The form of colony seems to have been free, laminate or broad and Flustra- 

 like. Tiie small, dried fragment that I have examined of this form shows ai)out 

 50 rows of zooecia. It originates from North Australia and was given me by 

 the late Mr. C. N. Peal. 



The two species of the genus Eiilhijroides dilfer so much from all other asco- 

 phorous forms, that it has been necessary to refer this genus to a new family, 

 the nearest relatives of which must undoul)tedly t)e sought in the family Cribri- 

 liiiiilac and especially in the genus Eigulina. The two species agree with this 

 genus in regard to the structure of the rosette-plates and the presence of two 

 large fenestra' in the oa'cia. The avicularium found in E. Jcllijde quite corre- 

 sponds with that found in the Fiyiilina species, and in most of the latter the 

 form of the aperture is similar to that in the two just-mentioned species. There 

 are other points of similarity, such as tlie well-developed hinge-teeth and the 

 spines which are provided with a pore. In /•'. chlilhrididta Waters the number of 

 spines may sometimes be reduced to 3 on each side. — With regard to the struc- 

 ture of the ooecia the tertiary Membraniporellti leiuiicosla described by Mac Gillivray ', 



' 70, p. 56. 



