265 



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

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

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

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

 these spines are not yet present, and the operculum (fig. 8 b) at this time 

 is proximally surrounded by a calcareous belt, separated 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 spines 

 gradually develop and cover the decalcified portion. Such a process does not 

 seem to take place in E. episcopalis. 



The ooecia are high, strongly arched, almost oviform, and the ectoooecium 

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

 side the narrow central belt there is a longitudinal ridge joining the endoooecium. 

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

 in E. episcopalis 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 mandible 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. The small, dried fragment that I have examined of this form shows about 

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

 the late Mr. C. N. Peal. 



The two species, of the genus Euthyroides differ 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 undoubtedly be sought in the family Cribri- 

 linidae and especially in the genus Figulina. The two species agree with this 

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

 large fenestrse in the ooecia. The avicularium found in E. Jellyae quite corre- 

 sponds with that found in the Figulina 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 the well-developed hinge-teeth and the 

 spines which are provided with a pore. In F. chlUhridiata 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 Membraniporella tenuicosta described by Mac Gillivray S 



'■ 76, p. 56, 



