SUMMARY. 



183 



Family XL— TROPIDASTERIDvE, Wriglit (Vol. II, p. iii). 



Body stellate, rays variable in number, short. Upper surface spinous. Ambu- 

 lacra bordered by transverse plates with spiniferous crests on their anterior margin. 

 Two rows of pores on each ambulacral space. Anal opening present. Family ranging 

 from the Lias to the existing period. Represented in the British Liassic and Oolitic 

 strata by two genera (Tropidaster and Solaster) and two species. 



Gems 23. — Tropidaster, Forbes (Vol. II, p. 102). 



Body stellate, rays five, short, convex, bearing on the upper surface a central 

 carina of a double series of squamose plates with lateral ranges of spines. Ambulacral 

 grooves rather broad, lanceolate. Ambulacral ossicula oblong, rather broad, strongly 

 bent and crenated on the sulcal border. Marginal plates crested and bearing a row of 

 spines. Two rows of ambulacral pores. Anal opening on dorsal surface (?). Genus 

 found in the Lias. One British Liassic species (Vol. II, p. 102). 



Genus 24. — Solaster, Forbes (Vol. II, p. 104). 



Body stellate, rays numerous, short, bearing on the upper surface fasciculated spines. 

 Ambulacral grooves wide and deep. Marginal plates crested^ bearing a row of long 

 slender acicular spines. Two rows of ambulacral pores. No pedicellaria3. Anal 

 opening central. Range of genus from the Oolitic to the existing period. One British 

 Oolitic species (Vol. II, p. 104). 



Family XIL— GONIASTERlDiE, Wri(/ht (Vol. II, p. 7). 



Body pentagonal, angles more or less produced, somewhat flattened on both sides, 

 margins conspicuous. Upper and under surface central. Ossicula small, flat, hexagonal, 

 pentagonal, tetragonal, covered with granules, spines, or pedicellarise. Marginal plates in 

 a single series on each surface, large and granulated. Ambulacral avenues bordered by 

 a series of square ossicula, often marked by parallel grooves for lodging the spines. 

 Two rows of ambulacral pores. Anal opening on upper side, excentric. Family ranging 

 from the Lias to the existing period. Represented in the British Oolitic strata by two 

 genera (Goniaster and Stellaster) and three species. 



