FROM THE MEROUI ARCHIPELAGO. 



123 



with the woodcut, may be sufficient for identification should the 

 species occur again. The specimens were small and immature, 

 and did not enable me to determine with certainty the habit of 

 growth, but it seemed to be eminently simple. 



In one or two cases a cell was present on each side of one of 

 the zocecia in a main shoot (see Woodcut), which was probably 

 the commencement of a branch. 



The zocecium is clavate in figure, elongate-ovate above, and 

 produced below the aperture into a peduncular extension. 



It is impossible to determine the systematic position of this 

 form with certainty in the absence of a fuller diagnosis, but it 

 will rank amongst the Bicellanidce, and probably in the genus 

 Bugulella of Verrill. 



Family Steganoporellid.1. 



Thalamoporella, HincJcs *. 

 Thalamoporella Smittii, Hincks. 



Syn. Steganoporella Smittii, id. History Brit. Mar. Polyzoa. 

 p. 178, plate xxiv. figs. 5, 6. 



Hab. On stone, forming a large spreading crust. 

 [Coast of Cornwall.] 



The Mergui Thalamoporella is undoubtedly identical with the 

 Cornish species. It also closely resembles T. Bozieri, Audouiu, 

 form indica, mihi ; the two forms only differ in the structure of 

 the avicularium. In T. Smittii the mandible is elongate and 

 spatulate ; the margin of the beak is elevated on each side in the 

 centre, and bends inwards at this point over the cavity, constrict- 

 ing the aperture and reducing it to a narrow passage. In T. 

 Bozieri, form indica, the avicularium is comparatively short, 

 rather broad and of about equal width throughout, and rounded 

 above. The essential structure of the mandible is the same in 

 both forms. It is composed of two distinct portions — a central 

 piece which is slender, somewhat incurved on each side a little 

 above the base, subacuminate at the upper extremity, and com- 

 posed of solid chitinous material ; this central portion is sur- 

 rounded by a membranaceous extension or edging, which fills up 

 the space between it and the stony framework of the beak. 



* I have proposed this genus for the section of Smitt's Steganoporella of 

 which Thalamoporella Rozieri, Audouin, sp., may be taken as the type. " Cri- 

 tical Notes on the Polyzoa," Ann. & Mag. Nat. Hist, for February 1887. 



