EEPOUT ON THE TETKAOTINELLIDA. 
851 
Genus 5, Poritella, 0. Schmidt. 
Founded on a deciduous specimen; generic characters not assignable. 
Poritella decidua, 0. Schmidt. 
Poritella decidua, O. Sclimidt, Spong. Meerb. Mexico, p. 27, 1879. 
Sponge. — Irregularly fan-shaped or vasiform, attached ; walls thick, upper margin 
flat, smooth; inner surface covered with small circular oscules, less than 0'5 mm. in 
diameter ; outer surface covered with pores, visible to the unaided eye. 
Spicules. — I. Megascleres. 1. Desma, large, very irregular in form, covered with 
large cylindrical and conical tubercles ; zygosis is lateral as well as terminal. The axial 
fibre of the crepis measures O' 044 mm. in length, the entire desma 0'5 mm. from end to 
end, 2. Rhabdus, slender, cylindrical ; termination (?). 
II. Microsclere (?). The specimens are deciduous. 
Size of fan-shaped specimen sent me by Professor Agassiz, 35 mm. in height and 32 
mm. in maximum breadth, walls 10 mm. in thickness. 
Habitat. — Various localities in the Gulf of Mexico ; 100 to 805 fathoms. 
Remarks. — This sponge very closely resembles in general appearance Corallistes typus, 
0. Schmidt ; it differs, according to Schmidt’s description, in the absence of trisenes. 
Genus 6, Amphibleptula, 0. Schmidt, 
Azoricidse with a single oscule at the summit, and poriferous areas borne at the ends 
of short cylindrical processes, irregularly and generally distributed over the sides. 
Amphibleptula madrepora, 0. Schmidt. 
AmpMhleptula madrepora, O. Schmidt, Spong. Meerb. Mexico, p. 28, pi. i. fig. 6 ; pi. iii. fig. 7, 
1879. 
Sponge. — Conical, with rounded sides, attached by a flattened or concave base, at the 
summit a flattened area about 6 mm. wide, presenting vertical radiating septa about 
twelve to thirteen in number, surrounding a central cavity about 1'5 mm. in diameter, 
into this and the cavities between the septa open numerous more or less vertical tubes. 
The sides for 5 or 6 mm, from the summit are plain and even, but beyond this 
covered with numerous, not very regularly arranged, cylindrical processes, 1 to 2 mm, in 
diameter, traversed by one or more tubes, which open by septate apertures at the end. 
These represent the incurrent openings, that at the summit the oscule. 
