112 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 50. 



d* Width of terguin more than half its length, the spur short, near the 

 basi-scutal angle; small barnacles. 



e. 1 Three pits in the inner side of the scutum Balanns glandula. 



e. 2 No middle pit in the scutum Balanus crenatus. 



c. 8 Wall without regular internal ribs; basis membranous; tergum narrow 



and long, with long, slender spur Balanus cariosus. 



b? Compartments of the wall without longitudinal tubes; tergum short, with 

 a short spur. 

 c. 1 Scutum distinctly striate longitudinally ; walls strongly ribbed. 



Balanus engbergi. 

 c. 2 Scutum weakly or not striate longitudinally. 



d. x Spur of the tergum tapering, less than half as wide as the basal mar- 

 gin of tergum ; upper part of the scutum thickened within. 



Balanus hesperius laevidomus. 



d? Spur very short and truncate, occupying half of the basal margin ; 



scutum with three pits inside Balanus glandula. 



MITELLA POLYMERUS (Sowerby). 



Plate 20, figs. 1, 2. 



Piles of the dock at Olga (Cat. No. 53813, U.S.N.M.), and at the 

 promontory, Deer Point, forming the eastern entry to Obstruction 

 Pass. Abundant and typical. As this species was not figured in 

 United States National Museum Bulletin 60 or other readily acces- 

 sible work, photographs are here reproduced, natural size. 



BALANUS NUBILIS Darwin. 



Friday Harbor. In Puget Sound this species reaches its maximum 

 size, far larger than Darwin's original specimens. In a group of 

 four sent, the diameter is between 90 and 100 mm. (Cat. No. 53811, 



U.S.N.M.) 



BALANUS CRENATUS Bruguiere. 



Patelliform, columnar, and club-shaped specimens, the latter like 

 the well-known club form of Bahtmi* baldnoides. Friday Harbor. 

 (Cat. No. 53805, U.S.N.M., 30 specimens; Cat. No. 53806. U.S.N.M., 

 6 specimens; and Cat. No. 53808, U.S.N.M., 4 specimens.) 



BALANUS GLANDULA Darwin. 



Large examples up to 25 mm. long, similar to plate 43, figure 5, of 

 Bulletin 93. Friday Harbor (25 specimens, Cat. No. 53810, U.S.N.M.) 



BALANUS CARIOSUS (Pallas). 



Plate 20, figs. 3. 6. 

 Friday Harbor. Very abundant (Cat. Nos. 53802, 53803, 53804, 

 and 5380T, U.S.N.M.). Old specimens are deeply eroded, cylindric, 

 with rather thin walls at the base, not showing as many pores as in 

 the conic typical form. A crowded, columnar form of small diam- 

 eter is also abundant; length about 55; diameter, 5 to 15 mm. As 

 this seems to be an unusual form elsewhere it is figured (pi. 20, 



