I have nothii idd to Darwin's excellent description of t h i-. species, neither for the 



hermaphrodite form nor tor the complemental males. Darwin discovered that the latter were 



attached in this sp to the integument <>f the hermaphrodite, in a central line, between the 



im and the adductor scutorum muscle, three individuals in a group. < tpening the capitulum 



specimens I found the little males at once al the place indicated by 



>nly difl being that 1 found not three 1 >ut four of them attached t<> the 



hermaphrodite. Th< I form of the complemental male and of its rudimentary valves 



and scutum are in the main as described by Darwin. The largest specimen measured 



to Darwin its length is of an inch = o,8<> mm.). The scutum is 



narrow; it is considerably smaller than that in Darwin's figure, but it has exactly th« 0,2 mm.) 



which it should ha> irding t" Darwin's description. The whole of the sar, which represents 



ombination of capitulum and peduncle, is covered with very minuut hairs. Beneath the 



rudiment rina and down the peduncular part of the sai are planted numerous much longer 



spines which to a large extent are bifid at the extremity. The fig. 13 of PI. V has been 



drawn with the camera from the largest of the specimens. 



Darwin's specimens were from the Philippine Archipelago, Island of Bantayan, attached 

 to a horny coralline: 20 fathoms (about 36111.). The "Siboga" collected it at the followingpla 



Stat. 47. April 8 — 12, [899. Bay of Bima (North Coast of Sumbawa). Depth 13 — 55 m. 



Numerous specimens. 

 Stat. 204. September 20, [899. Lat. 4°2o'S., Long. I22°58'E. Depth 75 — 94111. Bottom: sand 



with dead shells. 2 specimens. 

 Stat. 213. Sept. 2 I >t. 26, iSyy. Saleyer anchorage and Surroundings. Depth down to 36 ra. 



Bottom: coral reefs, mud and mud with sand. 6 specimens. 

 Stat. 294. January 23, 1900. Lat. 10° 12.2 S., Long. i24°27'.3 K. Depth 73 m. Bottom: soft 



mud with very fine sand. 6 specimens. 



5. Scalpellum Peroni (Gray). PI. V, fig. 14, 14.-/, \\B. 



Smiliutn Peronii J. E. Gray, Anaals of Philos. New series, X, 1825. 

 Scalpellum Peronii Darwin, Monograph. Lepadidae, 1S51, p. 264, pi. VI, fig. 6. 



I refer to this species the specimens of Scalpellum which were collected by the scientists 

 of the "Siboga" Expedition at the Jedan Islands. Most probably the place where they were 

 found is the anchorage off Palu Jedan, east coast of Aru Islands Pearl Banks 



There are in all three specimens, one of which is extremely small. The largest one has 

 been figured; it has a total length of 22 mm. and a capitulum of 13 mm. It is considerably 

 smaller than the specimens investi^ated by I)\k\vin, which had a total length of little more 

 than <>ne inch (25,4 mm.) and the capitulum of which measured about three epiarters of an inch 

 1 mm.). Perhaps the differences between the description and li-nre given by Darwin and the 

 from Jedan must be ascribed to the circumstance that the latter specimens are not 

 quite full-grown. 



These differences are in the- first place, that the spines which clothe the membrane 



the valves and the interspaces are by no means so strong and se. dense as they are 



figure given by Darwin; and secondly, that the rostrum and the subcarina, 



