the Cirripede Genus Stramentum. 71 



/S. pulchellum. A MS. label is on the specimen bearing; the 

 Avords '• Lorlcula pnlchella," and I can see no cliaractcrs in 

 the specimen to make one dissent from that determination. 

 S. macadaini is therefore considered here to be a synonym 

 of S. jmlchellum, 



Measiirenienfs.^-The largest species appears to be S. pul- 

 chellum. The liolotype has a length of 26'6 mm., its breadth 

 is 15'2 mm., and the length of the scntum is 8G mm. This 

 is snrpassed by the two specimens (PI. III. figs. 1, 2) originally 

 described as S. darwini, for the original of fig. 1 has a length 

 of o5'2 mm. (incomplete), a breadth of 22 mm., and a 

 scutnm 11 '4 mm. in length, while the original of fig. 2 has 

 a length of 44 mm., a breadth of 22*4 mm., and a scutum 

 of 13"2 mm. in length and 7'Q mm. in breadth. In the latter 

 specimen the carina is 6"8 mm. long and 2'3 mm. wide. 

 The original of S. macadami has a length of 24*6 mm. 

 and a breadth of 12"3 mm. « 



Of the other species the type of S. haworthi is said to 

 have a length of 27 mm. and a breadth of 17 mm., and the 

 type of S. tabulaiuin appears to be somewhat smaller ; 

 S. canadensis is from 14-15 mm. long and 7 mm. wide; 

 S. pulchellum var. minor is said to attain a length of 20 

 mm. and S. pulchellum, var. giyas, a length of 30 mm. ; 

 S. lavissima has a length of 20 mm. ; and S, syriacuni is 

 said to be one-third the length of S. lavissima. 



Terminology and Number of Valves in the Capitulum. 



Darwin had only a single specimen of the genus before 

 him, namely, the liolotype of S. pulchellum, and while this 

 was nearly complete so far as the peduncle was concerned, 

 it had only tbree of the capitular valves (see PI. III. fig. 3). 

 That on the right, owing to its shape and to the direction of 

 its growth-lines, was considered by him to be the scutum 

 and the adjoining plate as the first or upper latus. The 

 remaining valve was called the second or carinal latus, but 

 between that and the upper latus was a hiatus, believed 

 by Darwin to have been filled by a tergum. Besides these 

 valves he included in his restoration a carina and a rostrum, 

 making ten valves in all, for he assumed that the other 

 valves were paired. 



The specimen of S. macadami figured and described by 

 Wyville Thomson seven years later was more complete in 

 the capitular region, and it included a valve — the tergum — 

 not present in the holotype of S. pulchellum, between the 

 upper and carinal latera, as well as two opposing linear 



