THE SESSILE BARNACLES. 33 



VERRUCA CALOTHECA Pllsbry, 

 Plate 4, figs. 4, 4a, 46. 

 1907. Verrum calotheca Pilsbry, U. S. Nat. Mua. r>ull., GO, p. 110, pi. 11, figs. 1-3. 



Type.— Cat. No. 32907, U.S.N.M. 



Type-locality. — Albatross Station 2415, north Lilitudo 30° 44'; 

 west longitude 70'^ 26', off Georgia, 440 fathoms, bottom tempera- 

 tm'o 45.6 F., on Calantica superha. 



The type-specimen, the only one known of the typical form, is 

 figured hero (pi. 4, figs. 4-46) to show certain features not noticed in 

 the original account. The suture between fixed scutum and fixed 

 tei^uni is of the usual structure — a slit, widening upward, occupied 

 by a very narrow radiiform extension of the fixed scutum and above 

 it an obliquely grooved aliform triangle for the fixed tergmii. 



The movable acutmn has four articular ribs (in addition to the 

 usual apical rib, which is very slender and short, arliculating above 

 the first tergal rib). The lower or fourth rib temiinatcs at the basi- 

 tergal angle. Inside there is a deep articular furrow. The interior is 

 deeply concave, with a distinct, rounded adductor pit; near the 

 basal margin there are two grooves (fig. Aa). The scutotergal suture 

 is markedly sinuous. 



The movable tergum has four articular ribs and a weak ledge along 

 the occludent margin. Inside there are two basal grooves, as in the 

 scutum (fig. Ah). 



The rostrum has, above the upper articular rib, an area upon which 

 there are two slender ribs curving toward the movable plates. This 

 ribbed scutal area is shown in figure 1 of my former paper, but not 

 mentioned in the description. 



Internally (pi. 4, fig. 4) the waU-plates are beveled to a sharp, 

 simple edge. There is a very shallow pit or depression for the ad- 

 ductor muscle in the fixed scutiun, which is calloused below it. 

 The sutural edges of fixed scutum and tergum are decidedly thick- 

 ened. In the scutum this thickening is in the lower part of the wall, 

 but in the tergum it is chiefly farilier inward, spreading in a rather 

 thick pad in the upper part. 



Cirrus i has rami of 10 and 12 joints, the shorter ramus two-thirds 

 the length of the longer. Cirrus ii has the endopod slightly shorter, 

 more hairy, as usual. Cutus iii is similar, the outer ramus having 

 three pairs of spines on each joint. 



The terminal appendages have 14 joints, and arc very little longer 

 than the protopod of cirrus vi. 



Penis is about two-thirds as long as protopod, and has very 

 few hairs. 



Verruca alba Pilsbry is related to V. caloilieca, but differs by having 

 a distinct pit within the fLxed scutum, high on the waU near the 



