276 CEYLON PEARL OYSTER REPORT. 



antennae longer than the median (tentaculnm impar) ; ceratophore of the median 

 antenna normal, nearly one-third the total length of the antenna, less than one-half 

 the length of the ceratophores of the submediau antennae which are nearly one-half 

 the total length of these appendages ; ceratophores of the lateral antennse about 

 three-fourths the length of the submedian ceratophores, about two-thirds of the total 

 length of the lateral antennae. 



The above proportions, the moderate length of the median and the considerable 

 length of the submedian and lateral ceratophores are characteristic. The submedian 

 antennae stretch back over ten segments. The tentacular cirri were lost, one was 

 observed detached. Setae of the body -segments comprise 6 to 8 simple capillary with 

 two bidentate guarded acicular setae and three acuminate aciculas ; a small bundle of 

 fine capillary setae passes into the dorsal cirrus, sometimes extending far along the 

 cirrus. Dorsal cirri normal, subulate. Branchiae commence as a simple filament on 

 the first setiger and remain simple for 7 or 8 anterior segments, then becoming- 

 pectinate with 5 or 6 processes. 



The first setiger contains the dorsal bundle of setae for the dorsal cirrus and a 

 ventral fascicle comprising one simple capillary seta, six characteristic tridentate 

 compound setae and an acicula (Plate IV., figs. 98 and 99). The second setiger 

 resembles the first, but contains in the ventral fascicle three simple setae and five 

 compound setae of the same type as in the first. The posterior lingule of these 

 anterior parapodia is long, acuminate, cirriform. 



This species is determined by the combination of characters afforded by the 

 ceratophores, setae, and branchiae. It occupies an intermediate position between 

 0. longissima, Gr., and 0. teres (Ehlers). The shape of the frontal antennae is also 

 important ; these are broad, almost foliaceous, divergent, subtriangular appendages, 

 neither filiform, fusiform, nor subulate. Their shape is liable to vary in different 

 states of contraction and only the combination of characters can be relied upon. The 

 setae give the best indications, the peculiar setae of the anterior parapodia and the 

 simple setae of the body -segments. 



Onuphis conchylega, Sars (1835). 



Localities : South of Manaar, 8 to 9 fathoms ; and from Station LIL, Cheval 

 Paar, 3 to G fathoms. 



It is somewhat surprising to find this species which is common at Plymouth 

 occurring also off the coast of Ceylon. Its flattened tube, covered with large hori- 

 zontally placed shell fragments, is so characteristic that it is impossible to name it 

 differently from the type. This species should be the type of the unfortunate genus 

 North ia, of Johnston. I have carefully unravelled the confusion which this genus 

 has caused, and the result is that I agree with the Baron de St. Joseph that it should 

 be dropped. The species has wide distribution (see Ehlers, ' Florida- Anneliden,' 

 1887, p. 73) and is synonymous with Diopatra eschrichti ((Erst.). 



