A EEVISTON OF THE GENUS STEGANOPORELLA. 257 



is situated rather more distally than in most species. The 

 submargiual teeth are strong, and are borne on a distinct 

 sclerite, which commences near the base of the operculum. 

 Their number varies from about thirteen to about twenty, 

 the proximal ones being minute. Eighteen may be regarded 

 as the average number. The operculum is always broader 

 than long, though the disproportion between the two measure- 

 ments is sometimes a good deal less than in fig. 18. The size 

 varies as much as the shape, but without altering the general 

 characters of the operculum. The diameter varies from 450 

 to 700 fi, that of the specimen figured being 570 fi, which is 

 almost exactly the average of the specimens measured. 



(ii) B Opercula apparently wanting. a Opercula 

 with four teeth on the main sclerite, the 

 proximal pair being derived from the occlusor 

 tubercle. 



6. S. auriculata, n. sp. Figs. 8, 24. 



Cryptocyst inserted near the junction of the distal and 

 basal walls, usually joining the distal wall, but sometimes 

 joining the basal wall ; not angulated at the commencement 

 of its descending portion. Median process with enormous 

 auriculate lateral wings; uniting distally with the large con- 

 dyles, which project into the subopercular space as con- 

 spicuous points. A curved " opesiule,'' for the passage of 

 tendons, is thus formed on each side. The opening of the 

 tube is nearly vertical, and is invisible from above. Cavity 

 of median process very broad above, diminishing almost to a 

 point below, b zocecia not found, a opercula with four 

 enormous teeth on the main sclerite ; a broad and excessively 

 strong transverse, sub-basal sclerite connecting the bases of 

 the two proximal teeth. 



Madagascar : T. W. Waters^ Esq. (B. M., 84.11.18, 1). 



The specimens of this species are — (a) an imperfect colony 

 on a red seaweed, Hemescharan in character, forming an ex- 

 panding flattened collar which encircles the narrow stem of 



