30 BULLETIN 60, UNITED STATES NATIONAL MUSEUM. 



umbones of carinal and inframedian latera. The capituluin is covered 

 witli a rather thin 3'ellowish-gray cuticle, which is very shortly and 

 delicateh' pilose, the pile hardly noticeable, and worn from the older 

 portions of the valves. The scutum is like that of /S. regiunt., except 

 that the upper part is less acuminate. The carina is flat on the roof, 

 anoular or with low ribs laterally, the sides spreadino- a little. The 

 base and g-rowth lines are V-shaped, as in n^ytum. The roof is not so 

 wide as in S. rcg'nim Jaf /dorsum. The upper latus is like that of 

 S. reglmn., except that its carinal l)order is longer. The rostrum is 

 narrow and indistinctly visible through the cuticle. Rostrallatus 

 is decidedly lower in comparison with its width than in S. reglum. 

 The triangular inframedian latus is much smaller, relativel}^ to the 

 size of the capitulum, than in S. regiam, and there is a roof-like chiti- 

 nous extension above its apex not noticed in S. reglmn. The carinal 

 latera are comparatively lower than in reglmn., with a strongly recurved 

 und)o, above which there is a chitinous extension of the plate, which 

 extends also along the upper margin. The peduncle has larger scales 

 than in S. regimv, and is less pubescent. There are T rows of about 

 9 scales each. 



Length of capitulum, 48; breadth, 31; length of carina, 43; diame- 

 ter near base, 9.5 mm. ; length of peduncle 21 mm. 



The largest specimen of the lot measures — length of capitulum (30, 

 breadth 38, length of peduncle 36 mm. It is one of the largest species 

 of the genus. 



The cirri (of the largest specimen seen) are dark brown, the tirst pair 

 blackish. Branches of the first cirrus (Plate IV, fig. 1(») unequal, with 

 11 and 13 segments, those of the anterior branch very short and broad, 

 wider than in S. regimn. Cirrus ii is shorter than the following, with 

 subequal branches of about 26 segments. The other cirri are some- 

 what longer and subequal. The joints of the sixth cirrus have 5 or 6 

 pairs of long bristles along the anterior margin, with numerous fine 

 short bristles between the major ones of each pair. The arrangement 

 is not unlike that figured for 8. dearnsU.^ except that there are more 

 small bristles. The caudal appendage consists of 5 indistinct seg 

 ments, each with a bunch of bristles, the last terminating in a group 

 of long spines (Plate IV, fig. 14). The individual examined had no 

 penis. 



The mandible (Plate IV, fig. 12) has four teeth, the lower one very 

 bluntly truncate, the spaces between the teeth being sul)equal, not 

 unequal, as in the example of S. reglum, examined. The maxilla has 

 a single large upper spine and a straight, closelv spinose edge (Plate 

 IV, fig. 11). 



A young example has pale, corneous cirri. Whether the differences 

 between this form and S. reglmn found in the cirri and mandibles 

 would prove constant in a large series remains to be seen. 



