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covered with mud, I think it is easily possible to overlook them: the species is perhaps more 
common than we suppose at present. In 1908, I received from Dr. van Kampen, who was 
at that time in Batavia, specimens of the same species, dredged at a depth of + 45 m. in 
the Malay Archipelago: Lat. 6° 15’S. and Long. 110° 50’ E. 
19. Balanus qguinquevittatus n. sp. Pl. XXII, fig. 3—r10. 
Shell conical, greyish-white, having five brownish spots on the rostrum, the latera and 
the carino-latera, and six small apertures immediately above the basis and between the sutures of 
the compartments. Scutum with the lines of growth smooth, tergum with the apex not produced. 
This interesting form in certain respects approaches the genus Acasfa; it belongs, no 
doubt, to the same group of species as B. guadrivittatus, B. terebratus, and several other species. 
It was found attached to the shell of a Gastropodous mollusc. 
The general shape is conical (Pl. XXII, fig. 3), with the compartments smooth, not 
folded or ribbed. The orifice is pentagonal, small, hardly toothed. The carino-lateral compart- 
ments are narrow. The radii are very narrow and have oblique summits. The colour of the 
shell is dirty white and is not covered by a membrane. Near the orifice, all the compart- 
ments, the carina excepted, show a brownish spot, the colour of which corresponds with the 
bands observed in &. guadrivittatus. The basal margin of the different compartments is 
irregularly toothed; in the lower half the compartments are separated from each other by 
apertures of a longitudinal shape, about the same distance being occupied in the upper half 
by the radii. This gives the whole of the shell a very peculiar appearance and resembles, 
more or less, what is seen in Acasta fenestrata. The basis is thin, calcareous, and has no 
pores, so far as I could make out. The longest diameter of the basis measures 5.2 mm. in 
the largest specimen, slightly over 4 mm. in a smaller one. 
The scutum (Pl. XXII, fig. 4, @ and c) has the lines of growth only feebly indicated. 
It has the basi-tergal angle rounded, no adductor ridge, and the articular ridge narrow, not 
prominent. 
The tergum (Pl. XXII, fig. 4, 6 and d) has the spur broad, bluntly pointed at the 
extremity. The basal margin is slightly hollowed out, the scutal margin straight, the apex 
pointed without being produced. The anterior margin of the spur makes an angle with the 
extremity of the basi-scutal margin. 
With regard to the structure of the animal’s body the following is to be noted: 
Mouth. Labrum (Pl. XXII, fig. 5): notch deep and narrow, entrance only slightly 
wider. Lateral parts, on each side of notch, have an arched or curved outline. Three very small 
indistinct teeth are disposed between extremely short hairs on each side of notch. Shape of the 
thickened chitinous portion, which in other species of Ba/anus is sub-triangular, rhombiform: 
height and breadth nearly equal. | 
Palpi: of peculiar shape, with the upper margin straight and the lower margin convex, 
the two margins meeting in a rounded-off angle. The whole palpus rather narrow. Shorter hairs 
are disposed along upper margin, longer ones irregularly scattered over distal half of outer 
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