2l8 



Only a couple of specimens were taken ; this happened at : 



Stat. 164. August 20, 1899. Lat. i°42'.5 S., Long. I30°47'.5 E. Depth 32 m. Bottom : sand, 

 small stoncs and shells. 



General Remarks. This species is 110 doubt closely related to D. quadrivittatus, 

 which was dredeed at the same station. I have been obli^ed to consider and to describe it 

 as a distinct species, finding that not only the outward shape of the shell was different, but 

 that the structure of the animal's body showed some very characteristic and remarkable dif- 

 ferences. As already pointed out, the Station 164 is one of those where several species of 

 Balanus, as well as other genera of Cirripedia were collected. 



20. Balanus Jiystrix n. sp. PI. XXII, fig. 11 — 18. 



Shell dirty white, the other valves indistinctly, the carina distinctly ribbed longitudinally ; 

 orifice pentagonal, somewhat toothed. Radii triangular, with their summits oblique, striated 

 horizontally. Scutum with a deep longitudinal groove parallel to the occludent margin, and 

 with the articular ridge not prominent. Tergum with the longitudinal furrow open, and the basal 

 margin forming a straight line on opposite sides of the spur. Inner faces of the middle segments 

 of the cirri of the third, fourth and fifth pairs with several rows of teeth. 



This small Balanus (PI. XXII, fig. 11) has a rather depressed, globulo-cylindrical 

 shell, being only slightly narrower at the large pentagonal orifice than at the basis. The orifice 

 is indistinctly toothed, the surface is feebly-ribbed longitudinally, the carina, however, shows 

 rather deep longitudinal ribs, the bottom of the furrows between these ribs being coloured dark 

 blue or blackish. The radii have oblique summits, their surface is striated with lines parallel to 

 the basis, their free edges are distinctly serrated. The summits of the alae are also oblique 

 and are feebly rounded. The shell is thick and is strongly ribbed on the inner surface. It is 

 perforated by a single row of rather wide quadrate canals, some of which seem to be open near 

 the basis. The radii show traces of horizontal tubes or canals between the well-developed 

 septa. The basis has numerous ridges radiating from its centre ; they correspond with septa 

 extending in the same direction and separating the canals of the basis from each other. 



The colour of the shell is dirty white ; here and there rudiments of a yellowish epidermis 

 are seen attached to the surface. It seems to be a small species : the greatest diameter of the 

 largest specimen collected measures 5 mm. at the basis. 



The scutum (PI. XXII, fig. 12, a and c), is of ah elongately triangular shape and has 

 the occludent margin strongly and sharply serrated; its tergal margin is feebly convex, its basal 

 margin markedly so. The growth-ridges are not very prominent on the outer surface, but the rather 

 deep longitudinal groove which extends parallel to the occludent margin is very characteristic, 

 especially as there is a slight ridge or ledge between it and the occludent margin. As the 

 growth-ridges pass transversely over the furrow, they divide it into a series of pits, which, 

 however, are not very distinct. On the inner surface the articular ridge is not very prominent 

 and extends over two-thircls of the length of the tergal margin. The cavity for the adductor 



90 



