ISS 



Nvitli lateral margins curving outwards, and has likewise two lateral expansions, 

 which are separated from the niandihular cavity hy the triangular opercular 

 arch. The marginal portion of the mandihle is chitinized to an unusual degree. 

 This species, which incrusts a red alga from Madagascar, belongs to the Mu- 

 seum of Zoology at Cambridge, and has been kiTidly lent me for exaiuinaliou of 

 Dr. S. Harmer. 



Thalamoporella granulata n. s|). 



(I'l. VI :i, lit^s. 1, 2; I'l. VI, 11}^. .')). 



The length of the zooecia may vary between (),')',V2 and (),9;{""" The aperture, 

 the size of which may be contained S'/a — 4 times in the whole length of the 

 zooecium, has a broad and deep sinus, which is generally separated from (be 

 remaining semi-circular or semi-oval part by strongly developed hinge-teeth. The 

 proximal margin of the opercidum has on either side an extremely short chilinous 

 sclerite. The two indistinctly marked adoi^d areas are usually slightly ileveloped, 

 but may be furnished with small, round acropetal sj)ines. The two opesiula* 

 show as a rule no great difTerence in size, and llie oj)esiular outgrowths both 

 reach the i)asal wall, meeting it in two open hooked lines, which may l)e ecju- 

 ally large. The frontal wall of the polypide-tube is not very deeply de|)ressed, 

 and the cryptocyst, which has a strongly developed, crenulated or tuberculated 

 marginal part, is on the whole of its frontal surface more or less strongly tuber- 

 culous. Numerous, rather large pores. 



Spicules occur both in the shape of compasses and curves, and particularly 

 the latter show rather a wide range of variation. The smaller spicules are also 

 found between the cryptocyst and the covering membrane. 



The ooecia, which are without pores, have a rounded triangular outline and 

 a somewhat projecting aperture. The gonozooecia are of about the same size as 

 the ordinary zoo^cia, and the chitinous arch of the operculum is not far from 

 the margin. 



The avicularia. which may reach and even exceed the length of the zoircia, 

 have a strongly developed distal cryptocyst. The mandible is sometimes narrow 

 and tongue-shaped, sometimes i)road and more or less regularly lyriform or 

 vase-shaped. 



Var. A. (stapifera). 



(I'l. VI, li^s. 5a— 5 e). 

 The zo<Ecia, whose length generally varies from 0,798 to 0,9;5'""' , are most often 

 of a rounded hexagonal form, frequently unusually l)road and Hal. 'i'he adoral 



