224 
Darwin did not have the material with which to investigate the body of this animal. 
The small specimen from the Malay Archipelago, which can hardly be considered full-grown, 
furnished me with the following details: 
Mouth. Labrum (Pl. XXIII, fig. 2): with three teeth on each side of the wide, 
triangular notch. The thickened sub-triangular shield is high, its height equalling the width. 
Palpi: ovate with the lower margin more strongly bowed than the upper margin. 
Longer hairs on outer surface very few: 4 or 5 arranged in a longitudinal row which makes 
a very sharp angle with the margin near the free extremity. The upper margin bears a series 
of not very numerous hairs, diminishing in size towards the attached basis of the palpus; the 
hairs seen on the inner surface short and not numerous. 
Mandible: much like that of 4. calceolus; five teeth and an-inferior angle, the latter 
terminating in two extremely small flat teeth. 
Maxilla (Pl. XXIII, fig. 3): same structure as in B. calceolus, free edge rather broad 
and furnished with 2, 3 and 2 spines. Notch small, has a single hair or delicate spine situated 
at its base. Upper margin of maxilla very strongly curved, shape of the whole triangular, 
apodeme relatively long. 
Outer maxillae: as in 4. calceolus, outer lobe slightly more elongate. 
Cirri. First pair with very unequal rami, of 5 and 9 segments respectively. 
Second pair with slightly unequal rami, of 5 and 6 segments respectively. 
Third pair with somewhat more slender and also slightly unequal rami, of 6 to 7, 
and 7 to 8 segments; no trace of teeth to be seen along or near anterior face of the segments, 
or on the longer or the shorter ramus. 
Fourth pair with unusually short rami, of 10 and 12 segments respectively. 
Fifth and sixth pairs have the rami longer: although the number of segments is 
11 to 12 only, the segments are more elongate. The greatest number of pairs of spines observable 
on the inner faces of the segments is three; in some of the middle segments, however, a 
fourth extremely minute pair can be distinguished. Hairs seen on outer surface of segments 
near the extremity forming a small group, one being much longer than the others. (The cirri 
show more distinctly, I think, than do the parts of the mouth, that the specimen is a young one.) 
Penis very long, tapering towards extremity, and bearing only a few and very 
minute hairs. 
The specimen was collected at: 
Stat. 144. August 7/9, 1899. Near the Anchorage north of Salomakiée-(Damar-)Island. Depth 
45 m. Bottom: coral and Lithothamnium. 
Geographical Distribution: Darwin saw specimens of this species only from 
Tubicoreen, Madras. According to Werner, the Berlin Museum has specimens from Singapore, 
attached to Széerogorgia suberosa. 
23. Balanus investitus n.sp. Pl. XXIII, fig. 4—11. 
Parietes and basis with pores, radii without pores. Scutum with adductor ridge; tergum 
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