NO. 1555. ITAWAIIAN IIOLOTIIVRIANS— FISHER. 717 



those in sole by having many comparatively and actually smaller per- 

 forationvS, They vary from oblong- to triangular, oval, or irregular, 

 and some are to l)e classed as rods. These plates are smooth, but 

 comparatively few of the largest which have the central holes con- 

 spicuously larger than the rest have a few knobs on the surface. 

 Plates of this type (tig. If) attain a major diameter of 0.22 mm., 

 though most of them are shorter than this. The large rods in the 

 stem of the tentacles (It) attain a length of 0.5 mm., but many are 

 considerabl}' smaller. They are usually slenderer than lig. !<?, with 

 fewer perforations. In the smaller branches of tentacles are smaller, 

 crowded, irregular, perforated plates, similar to but smaller than the 

 perforated plates in perisome surrounding base of tentacles. They 

 are much more irregular in shape. 



The presence of large regular oral valves and of the two rows of 

 pedicels on lateral ambulacra allies this form to 7's. nfdrcilcus 

 (Philippi), tubercidosus Theel, epldppifer Wyville Thomson, and 

 diomede» Ludwig, from all of which it is separated by the very nar- 

 row region between mouth and anus, there being but two rows of 

 large plates intervening. The dorsal plates, are relatively larger than 

 in dloDiedex and the granules smaller and more numerous. There is 

 also a great difference in the size of oral and anal valves in macrolepls, 

 while the anal valves are quite different from those of dioinedex^ as 

 may be seen by a comparison of figures. " In rnacrolepis the oral 

 valves when closed are flush with the general surface of dorsum, but 

 in diomedese^ judging from the figure, are slightly raised. The 

 deposits also present points of difference, especially in the size of the 

 knobs on the plates these being large and conspicuous in dlomedex. 

 The present species may be readily distinguished from the other rela- 

 tives above mentioned by the two series of dorsal plates between 

 mouth and anus. Dlomedese^ from the vicinity of Cocos Island, 

 appears to be the nearest of kin. 



Order PARACTINOPODA Ludwig, 1891. 

 Family SYNAPTID.E Burmei.ster. 



Synaptid^ Buhmeister, Handbiioh der Naturgeschichte, 2. Ahtli. Zoologie, 1837. 



SuTjlkiiiily SYlsr^P'riN^K Owtoi-Ki-eii. 

 Synapdnir 0«tek(;ken, Ofv. Ak. Fori)., 1898, p. Ill (Daw System der Synaptiden). 



Genus SYNAPTULA Orsted. 



Synaptula Orsted, Synaptula vivipara, V^id. Meddel. Nat. Foren. Kj0l)enhavn 

 for 1849 ad 1850, 1851, p. 7. Type, Synaptula vivipara Orsted. 



ffMem. Mus. Comp. Zool., XVII, No. 3, 1894, pi. vi, figs. 1, 2, 3. 



