2% CEYLON PEAEL OYSTER REPORT. 



Family: SABELLARIID^. 



Pallasia pennata (Peters) Plate VIII. , figs. 1 and 2. 



Sabellaria pennata, Peters, "Ueber die Gattung Bdella Sav. und die in Mossambique 

 beobachteten Anneliden," 'Arch. f. Naturg.,' xxi., 1855, p. 42 ; also ' Monatsber. Berlin. 

 Akad.,' 1854, p. 613 (quoted from Gritbe, 'Ann. Semp.,' 1878, p. 220). 



Hermella bicomis, Schmarda, 1861, ' Neue Wirbellose Thiere,' p. 24. 



Locality : This worm occurs off the west coast of Ceylon either singly or in large 

 colonies, and builds a tube of coarse sand-grains cemented together, so as to form a 

 sandstone of excessive hardness which is capable of withstanding the full force of the 

 waves during the South-west Monsoon. It is evidently an important factor in the 

 preservation of the coast line. Sometimes the tubes are still further protected by a 

 Nullipore covering. The internal diameter of a large tube is about 6 millims. 



The specific name given by Schmarda refers to the presence of a pair of large 

 brown hooks bent towards the middle line, placed at the dorsal ends of the peristomial 

 lobes which, with their armature, constitute the paleal crown. There is usually only 

 one pair of hooks, but I have seen a specimen with three hooks (two on one side), 

 and Peters describes four hooks (two. pairs) in the single specimen examined by him. 

 Each peristomial lobe terminates anteriorly in a truncate dorso-ventral crescent- 

 shaped area, from the inner and outer arcuate borders of which the modified bristles 

 or paleae arise. The number of paleae in the inner row varies roughly between 20 and 

 30 ; the number in the outer row between 30 and 45. The paleae of the outer row 

 are long curved spines, slightly widened and strongly serrated along the distal three- 

 fifths of their length ; towards the apex of the palea the serrations are larger on the 

 concave border than on the opposite border ; all are directed towards the apex of the 

 palea. The palese of the inner row are acuminate, smooth, and more slender than those 

 of the outer row. In side view a series of 8 to 12 subulate papillae occurs below the 

 outer row of paleae, the most dorsal papilla being placed behind the hook on each 

 side, as shown in Mr. Watson's drawing (Plate VIII. , fig. 1). 



Dorsally the peristomial lobes are confluent across the middle line up to the level 

 of the hooks ; ventrally they are separated down to the level of the mouth. The 

 inner surface of each peristomial lobe is beset with numerous tentacular cirri arranged 

 in rows, the columns being indicated externally by crenulations of the ventral border 

 of the lobe (Plate VIII. , fig. 2). On each side of the mouth occurs the neuropodial 

 cirrus of the buccal segment, and at the base of this a bundle of capillary setae. The 

 second segment is distinct dorso-laterally, merging into the peristome below ; it 

 carries a bundle of neuropodial setae, above and adjoining which there is a triangular 

 lappet ; farther up the side follows another triangular lappet and dorsally the first 

 cirriform branchia (Plate VIII., fig. 1). The third, fourth, and fifth segments carry 

 on each side a neuropodial fascicle of long, rather narrow spatulate setae with laciniate 

 tips ending in a point, and a laterally placed notopodial fascicle of similar setae with a 



