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D. Aymonini Lessona et Tapparone Canefri, D. sinuata Aurivillius, D. trigona Aurivillius and 

 D. Vaillanti Gruvel. All these species agree in so far as they have rather narrow valves leaving 

 a great deal of the capitulum uncovered, and also in that the carina terminates downwards in 

 a fork. But here I wish again to emphasize, that though we must accept all these species for 

 the present I am not convinced that they really are so many or so distinct. 



The forms of Dichelaspis collected during the cruise of the "Siboga" belong to five 

 different species: D. Weberi n. sp., D. Nierstraszi n. sp., D. Tydcmani n. sp., D. Versluysi n. sp. 

 and D. orthogonia Darwin. The four new species are named after those who have the merit 

 of having done the scientific work on board the ship during the cruise. Of the new species 

 D. Nierstraszi and D. Tydeuiani are both nearly related to D. Warwicki Darwin and doubtless 

 belong to the same section of the genus; D. Weberi and D. Versluysi show — the latter more 

 than the first - - a well-marked affinity to Darwin's D. orthogonia. 



Thus we would now have 32 species of Dichelaspis, which might be classified according 

 to their mutual affinities in the following way : 



I. Species, in which the valves show the highest development, covering a great deal of the 

 surface of the capitulum. 

 D. sessilis (type-species), D. icnuivalvata and D. occlusa (3 known species). 



II. Species, in which the valves show a somewhat less development, with a relatively broad 

 scutum and the carina terminating in a rectangularly infiected disc. 

 D. Warwicki (type-species), alata, anliguae, equiua, Aurivillii, (Forresti), Hocki, Nier- 

 straszi, Tydemani (9 known species). 



III. Species, in which the valves are considerably less developed than is the case in the species 



of group II, in which however the carina has the same form as in the species of that group. 

 D. pellucida (type-species), Grayi, lepadiformis (3 known species). 



IV. Species having the same development of the valves as those of group III, but with a 



tergum corresponding in form to that of the species of group II. 

 D. orthogonia (type-species), Weberi, Versluysi (3 known species). 



V. Species with five valves, the narrowness of which causes a great part of the capitulum to 

 be uncovered. 

 D. Lowei (type-species), Aymonini, Darzvini, ncptuui, sinuata, trigona, Vaillanti (7 known 

 species). 



VI. Species with three valves only, terga wanting. 



D. cor (type-species), angulata, aperta, Coutierei, cuneata, Maindroni (6 known species). 



VII. Species with two valves only (terga and carina wanting). 

 D. bullata (type-species), 1 known species. 



Of these 32 species about one half (14, 15 or 16) have been observed in the Malay 

 Archipelago, viz. 



D. occlusa, East coast of Malay Peninsula: Tungganu (Lanchester). 

 D. Warwicki, off Borneo (Darwin), Java Sea, near Batavia (Aurivillius). 



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