CORBITELLA AND HETEROTELLA. 31 



8. Walteria flemmingi F. E. Sch. N. of Kermadec. 



9. W. leuckarli Lr. Sagami Sea. 



10. Dictyaulus elegans F. E. Sch. Indian Ocean. 



11. Diclyocalyx gracilis F. E. Sch. S. Pacific. 



Diagnoses of the Corbitellinœ described in this Contribution. 

 Genus Corbitella Gray. 



Corbitellinœ with sieve- plate ; saccular, thin-walled, phallus- 

 like. Lateral wall with numerous, round and irregularly arranged 

 parietal oscula. Spiny microxyhexactin present. Besides the 

 floricome and the graphiocome, there occurs a tolerably strongly 

 developed form of discohexaster in which each terminal ends with 

 a convex disc with strong, recurved, marginal prongs. 



Corbitella speciosa (Q. and G.). — Corbitella with body broad- 

 est at the arched upper end. Skeletal beams, including those of 

 the sieve-plate, fused together. Principalia parenchymalia probably 

 diactins ; accessoria diactins and hexactins. Discohexaster in the 

 ordinary hexaster form or in the hemihexaster form ; rarely 

 hexactinosc ; diameter 100-1 30/^, occasionally up to 145 g. Dia- 

 meter of floricome 72-So g. 



Corbitella elegans (Marsh.). — Quite like G. speciosa except 



in the following points : Discohexaster predominantly in the 



hexactinose form ; diameter 220-204 p-. Diameter of floricome 

 98-114/;. 



Corbitella pulchra (F. E. Sch.). — Corbitella with ventricose 

 body ; skeletal beams in the uppermost part of the wall arranged 



