58 UNITED STATES NATIONAL MUSEUM BULLETIN 251 



Rittei' (10-12 stigmatal rows and 10-12 longitudinal plications on 

 the stomach) from the Connnandor Islands group in Ihc Bering Sea. 

 However, the characteristic appearance of the colony in the present 

 specimens seems to differ from that of two species of Amaroucium. 

 A. coei Eitter from Alaska has 11-16 stigmatal rows and the appear- 

 ance of the colony somewhat resembles that of the present form, 

 though the test is quite free from sand grains. But the exact number 

 of the longitudinal plications on the stomach is unknown in A. coei, 

 which prevents a close comparison between these two forms. A. frag- 

 ile Redikorzev from the Okhotsk Sea has 10-11 stigmatal rows and the 

 colony consists of a number of cormidia encrusted with sand grains, 

 but the stomach is provided with only 4-5 plications. Above all, the 

 greatest difliculty in identifying the present specimens results from the 

 fact that the thorax is too strongly contracted to determme whether 

 the atrial aperture opens into the common cloaca or directly to the sur- 

 face. On the other hand, the colonial form of the present specimens 

 is met W'ith commonly in species of Ritterella ( '=SigUlinarla), known 

 chiefly from cool or cold waters. Especially the shape of each 

 cormidium and the consistency of the test in the present specimens con- 

 form very well with those of Amarouchnn aequalis'q^honis liitter and 

 Forsyth from the California coast ; stigmatal rows are 8-10 and longi- 

 tudinal plications on the stomach are never more than 6 or 7 in the 

 California species. There is still a slight gap in the number of stigma- 

 tal rows between the California species and the present specimens, but 

 I am inclined, at present, to regard the specimens described here, 

 provisionally, as a form close to A. aequalisij)honis. 



17. Euherdmania digitata Millar 



Figure 18 



Euherdmania dUjitulu Millar, 19G3b, p. 698, fig. 7. 



MATERIAL EXAMINED 



Palau Islands : Iwayama Bay, west shore of Island XXII opposite west penin- 

 sula of Island XX; 7°11)'3.5" N., 134°29' 53" E. (HO chart 607G, 2nd ed.) ; depth 

 3-10 feet, living and dead coral bottom ; GVF sta. 218, October 10, 1955 (USNM 

 11464). 



Description. — A single elongate specinion measuring 40 mm. in 

 length consists of only two zooids arranged as shown in figure 18a. 

 The portion containing the thoraces is somewhat stouter and raised 

 from the substrate, while the portion containing tlie abdomens is quite 

 thin, creeping on the surface of an empty shell. Both branchial and 

 atrial apertures open at the distal end of the zooidal sheath. 



Test rather hard, yellowish white and translucent; surface gen- 

 erally smooth, though wrinkled by contraction, quite free from for- 

 eign matter. Thoracic portions longer than 5 mm. Zooids 15 mm. 

 in length in a contracted state, of which 3.5 nun. constitutes the thorax ; 



