474 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



and greatly elongated to slender and scarcely or even not at all larger than P 3 or P,, 

 and it may be scarcely or even not at all longer than one or the other of these pinnules. 

 The proximal pinnules may be of approximately equal size on all the arms, or much 

 larger and longer on the outermost arms following a IBr axillary than on the other 

 arms, or they may be enlarged, or elongated, or both, on the outermost arms following 

 each 11 Br axillary, those on the outermost side of the postradial series being more or 

 less larger than those adjoining the midradial line. 



In the following pages the form of L. palmata with very slender lower pinnules 

 (gyges) is recognized as distinct for the reason that it has a more or less distinctive 

 geographical range, which, however, broadly overlaps the range of the typical form 

 (joalmata). Intergradation between the two forms is complete, and they are often 

 found together. 



The excessive variation of L. palmata is probably correlated with the highly 

 diversified conditions in its strictly littoral habitat, and there is no reason to assume 

 that characters which in this species are very variable are necessarily similarly variable 

 in other more or less closely related species. 



History. — In a revision of the family Mariametridae published in 19131 established 

 the genus Lamprometra with Antedon imparipinna P. H. Carpenter, 1882, as the geno- 

 type. The following nominal species were assigned to the new genus: aequipinna, 

 amboinensis, bremcuneata, conjungens, dwidua, gyges, heliaster, imparipinna, klunzingeri, 

 laevicirra, lepida, leucomelas, occulta, okelli, palmata, polyactinis, protectus, reginae, 

 scita, similis, subtilis, and tenera. Previously these forms had been included in the 

 genus Dichrometra established in 1909. 



The genus Lampnumlni is herein considered as including these same forms 

 grouped in two species, L. klunzingeri and L. palmata, the latter with two varieties, 

 L. p. palmata and L. p. gyges. 



KEY TO THE SPECIES AND FORMS IN THE GENUS LAMPROMETRA 



a 1 . Pi, and sometimes also P 3 , markedly stouter than the other proximal pinnules (Hongkong and 

 Philippines to Caroline, Marshall, and Hawaiian Islands, Fiji, Tonga Islands, New Cale- 

 donia, Solomon Islands, and Torres Strait, and westward to Baluchistan; 0-51 [?54] meters) 



palmata palmata (p. 474) 

 o*. All the proximal pinnules slender. 



b x . Basal segments of proximal pinnules strongly carinate (Marshall Islands, Samoa, and Fiji, 

 to northern Australia, south to Cape Hillsborough, Queensland, and Abrolhos Islands 

 and possibly Perth, Western Australia, and westward to Kabaeua Island; 0-35 meters) 



palmata gyges (p. 517) 

 W. Basal segments of proximal pinnules not at all, or only very slightly carinate (Red Sea east- 

 ward to Muscat and southward possibly to Zanzibar or Dar-es-Salaam; littoral). 



klunzingeri (p. 527) 



LAMPROMETRA PALMATA PALMATA (J. MUller) 



Plate 53, Figures 243-246; Plate 54, Figures 248-252; Plate 55, Figure 257 



[See also vol. 1, pt. 1, fig. 259 (centrodorsal), p. 255; fig. 477 (radial pentagon), p. 363; pt. 2, figs. 

 49, 50 (radial pentagon), p. 26; fig. 250 (arm), p. 199; figs. 472, 473 (pinnule tip), p. 269; fig. 

 720 (disk), p. 346.] 



t Caput- Medusae cinereum Linck, De stellis marinis, 1733, p. 57, pi. 21, No. 33. — Brugiere, Encyclo- 

 pedic m£thodique, 1792, pi. 125, figs. 1, 2 (copied from Linck). — J. Muller, Monatsb. prcuss. 

 Akad. Wiss., 1841, p. 185 (identified with a query as Alecto palmata, sp. now); Archiv fur 



