SUMMARY. 



179 



Surface of areas covered with numerous concentric rows of small perforated tubercles, set 

 close together on low crenulated bosses. Poriferous zones very narrow ; pores simple and 

 unigeminal, placed close together on the upper surface and wide apart at the base. Oral 

 aperture excentric near the anterior third of the base, oval, with the longer axis oblique. 

 Peristome unnotched, subpentagonal. Jaws absent. Anal aperture elongate, excentric, 

 in a longitudinal valley in the upper surface of the test, and in contact the apical 

 disc. Apical disc central, but not vertical, elongated. Anterior pairs of plates large, 

 and disposed side by side between the anterior and posterior ovarials. The posterior 

 oculars at the extremity of the posterior ovarials. Genus found in the Oolitic strata, 

 Three British Oolitic species (Vol I, pp. 298—303, but not pp. 292—296, see p. 465). 



Genus 17. — Galeropygus, Cotteau (Vol. I, p. 465). 



Test thin, similar to Hyboclypus, but possessing a subcompact, instead of an elongated 

 apical disc. Ovarian plates arranged in crescentric form around the concave anterior 

 opening of the round discal aperture, the right antero-lateral plate the largest, supporting 

 the madreporiform body; plates small, presenting acute angles, inserted into the notches of 

 the interambulacral segments of the discal opening. Ocular plates very small, inter- 

 calated between the angles of the ovarian plates. Range of genus from Lias to Oolitic 

 strata. Two British OoUtic species (Vol. I, pp. 292, 296 ; see pp. 465, 466). 



Family VIL— COLLYRITIDiE, Wric,M (Vol. I, p. 304). 



Test thin, ovoid, elongated or cordiform, depressed. Ambulacral areas narrow, and 

 so arranged that three meet at the larger portion of the apical disc, and two nearer the 

 anal opening, over which they form an arch. Ambulacra covered with small perforated 

 crenulated tubercles. Poriferous zones narrow ; pores unigeminal. Oral opening small, 

 oval, or circular, placed towards the sulcated border. Peristome entire. Jaws absent. 

 Anal opening small and oval. Apical disc elongate, subcentral, divided into two portions. 

 Three of the ocular plates are placed at the junction of the three ambulacra and two at 

 the junction of the other ambulacra. Family found in the Oolitic and Cretaceous strata. 

 One British Oolitic genus (Collyrites) and three species. 



Genus 18. — Collyrites, Beluc (Vol. I, p. 307). 



Test thin, ovoid, subovoid, or cordiform, depressed, slightly sulcated at the border 

 nearest the oral opening. Ambulacal areas narrow, straight, the five not in contact, at 



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