1 ) vrwin 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 (PI. 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. 



Pal pi: 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 B. calceolus\ five teeth and an inferior angle, the latter 

 terminating in two extremely small flat teeth. 



Max il la (PI. XXIII, fig. 3): same structure as in B. calccolus, 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 B. calceolus, outer lobe slightly more elongate. 



Cirri. First pair with very unequal rami, of 5 and 9 segments respectively. 



Se co nel 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 tracé 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. Salomakiëe-(Damar-)Island. Depth 

 45 m. Bottom: coral and Lithothamnium. 



Geographical Distribution: Darwin saw specimens of this species only from 

 Tubicoreen, Madras. According to Wfxtner, the Berlin Museum has specimens from Singapore, 

 attached to Suberogorgia stibcrosa. 



23. Balanus investittis n. sp. PI. XXIII, fig. 4 — 11. 



Parietes and basis with pores, radii without pores. Scutum with adductor ridge ; tergum 



96 



