1909.] MARINE FAUNA FROM MERGUI ARCUIPKLAGO. 899 



quaternaries form a similar though less conspicuous figure. The 

 third cycle is here also the least developed. There are three crowns 

 of pali, which are usually well marked oft' from the septal margins 

 and the columellar trabecul?e ; both pali and trabeculse are covered 

 with spiniform granules. The columella lies well below the 

 calicular margin, so that in this type there is a distinct though 

 narrow fossa. Intermediates between types I. and II. show less 

 obvious star figures, and the gradual reduction of the pali an(i 

 consequent development of the well-defined calicular fossa. 



Type III. 1 3 specimens. The *corallum is oval or i-ound, 

 15 mm. in diameter and 10 mm. high, and somewhat compressed 

 in the middle. The lateral pores form an irregular ring a little 

 below the calicular margin. Thecostfe ai-e as in the two previous 

 types. The septa form five cycles of six systems, of which the 

 primaries and secondaries are very much exsert round the margin 

 and the remaining cycles of about equal size, except those members 

 of the fifth cycle on either side of the primaries and secondaries 

 which are slightly enlarged. There are four crowns of nodular 

 pali cleaily marked oft" from the septa and standing well above the 

 trabecular columella ; all are ornamented with spines. The fossa 

 is large, 5x3 mm. and 2 or 3 mm. deep. Intermediate forms 

 connecting this type with type II. have an incomplete fifth cycle 

 of septa, or all the quinaries are very much reduced so as to be 

 hardly visible. 



Localities. — All three types occur at Station XXX. Fly Island, 

 Observation Island, and S.W. of Domel Island. Bottom : rock 

 and sand. Depth : 8-15 fathoms. 48 specimens of type I., 18 

 of type II., 7 of type III. 



Station XXXIII. Christmas Island Group. Bottom : rock, 

 sand, and mud. Depth : 8-23 fathoms. 1 specimen of type I. 



Family Flabellid^ Bourne [5]. 



In the present collection there are 29 specimens of the genus 

 Flabellu.m, which, since Gai'diner's [151 revision of the group, can 

 all be included in the highlj^ variable species F. ruhrtim. 



Genus Flabellum Lesson. 

 Flabellum rubrum Quoy & Gaimard. 



F. variahile Semper [34]. 



F. stokesi "] 



F. owe'id I 



F aculecUmn [ Milne-Edwards & Haime [27]. 



F. debile \ 



F. sumatrense j 



All the specimens are free, but with large and clearly defined 

 basal scars. They are truncate in form, the height of the 

 corallum being in all cases less than the length of the calice. 

 The margin of the calice is entire, the ends of the long axis are 



Prog. Zool. Soc.— 1909, No. LXI. 61 



