REPORT ON THE TETRACTINELLIDA, 
323 
character : they are largest and most remote in the type and in the specimen from Porto 
Praya, in both these they measure about 0'45 to 0'5 mm. in diameter; in the other 
specimen they are smaller, varying from 0'16 to 0’32 in diameter, and in their distances 
from one another they vary still more widely. In the specimen from Station 33 from 
four to six can be seen at one time in the field of the microscope, in that from Station 56 
as many as nineteen or twenty, and in that from Amboina about twelve. The size of 
the main excurrent canals and pores varies in correspondence with that of the oscules. 
The desmas are similarly variable, those in the specimen from Amboina are thicker, 
and more richly tubercled than in any of the others, including the type. These differ- 
ences are so marked, that it has been a question of much perplexity as to how far they 
should be recognised in our nomenclature ; since, however, in each case we have only 
individual specimens to deal with, and since it would be impossible to discriminate 
them without giving a specific name to each individual, I have thought it most 
convenient to group them together as a single species, adding here a summary of their 
differences, 
Azorica pfeifferse, Carter. Type, and specimen from Porto Praya. Sponge-wall 
comparatively thick, oscules large, marginate, desmas comparatively slender and smooth. 
Azorica pfeifferse tenui-lamiuaris. Specimen from Station 56 and Bahia, Sponge- 
wall comparatively thin, oscules small, closely approximated, desmas comparatively 
slender and smooth. 
Azorica pfeifferse tenui-laminaris, osculis disjunctis. Specimen from Station 33, 
Sponge-wall comparatively thin, oscules small, marginate, comparatively remote, desmas 
comparatively slender and smooth. 
Azorica pfeifferse intermedia. Specimen from Amboina. Sponge-wall intermediate 
in thickness between Azorica pfeifferse, type, and Azorica tenui-laminaris ; oscules small, 
closely approximated, desmas comparatively thick and highly tuberculated. 
The slight differences between the specimens do not appear to be correlated 
with differences of habitat, unless in the case of the specimen from Amboina ; the 
stouter form of desma in this being possibly connected with its occurrence in com- 
paratively shallow water (15 to 25 fathoms). 
Azorica marginata, n. sp. (PI. XXXV. figs. 14-22). 
Sponge. — Small, ear-shaped, attached, inclined so that the oscular surface is down- 
wards, the poriferous face upwards. Margins rounded, oscules simple, small, with 
circular, raised margins, 0'475 mm. in diameter. Pores simple, small. 
Spicules. — I. Megascleres. 1. Desma (ff\. XXXV. figs. 14-21), somewhat short and 
thick, densely tuberculated, tubercles bearing bifid spines. Total length of a curved 
form 0’238 mm,, of an elongated straight form 0'4 mm., a single branch of a quadriradiate 
