EEPOET ON THE TETRACTINELLIDA. 
179 
Supplemental Account of all other known Species of Stellettidh: not in the 
Challenger Collection. 
Subfamily 1. Homasterina, Sollas. 
Myriastra crassicula (Carter). 
Stelletta crassicula, Carter, Arm. and Mag. Nat. Hist., ser. 5, vol. vii. p. 371, 1881. 
Sponge small, spherical, attached ; oscules single, dispersed ; pores in sieves ; surface 
hispidated by projecting anatrisenes. 
Spicules. — I. Megascleres. 1. Somal oxea, fusiform, 2‘6 mm. long, 2. Ectosornal 
oxea, 0'317 mm. long. 3. Orthotrixne, rhabdome 2'6 by 0’07 mm. 4. Anatrisene, 
rhabdome 2 ‘6 mm. in length and over; cladome, chord 017 mm. long. 
II. Microsclere. 5. Chiaster, actines slender, not tylote, 0'0085 mm. in diameter. 
Colour. — Brownish-grey. 
Habitat . — Basse Eocks, Gulf of Manaar. 
Remarks. — Carter regards the ectosornal oxea as a microsclere, and speaks of it as 
characterising the sponge by its large size. No information is given as to the position of 
this spicule in the ectosome, but judging from some remarks which Mr. Carter was kind 
enough to send me supplementing his description, I conclude that it does not lie 
tangentially like the microxea of Papyrula, but radially like the ectosornal oxea of 
Ecionema or Anthastra. As the sponge does not appear to possess a cortex, and as the 
chiaster is the only form of microsclere present, I assign the species to the genus 
Myriastra. 
Myriastra siwplicissima (0. Schmidt). 
Ancorina simplidssima, 0. Schmidt, Spong. Ktiste v. Algier, p. 18, pi. iii. fig. 9, pi. iv.. fig. 9, 
1868. 
Sponge. — Massive, irregular, knoll-like, or pear-shaped, surface round; oscules 
numerous, canal system well developed ; cortex thin. 
Spicules. — I. Megascleres. 1. Oxea, fusiform, frequently somewhat suddenly bent 
in the middle, 2’7 by 0'08 mm. 2. Plagiotrisene, rhabdome conical, straight, 1'6 by 
0‘065 mm., cladi short, conical, not very sharply pointed, 0'2 mm. in length. 
II. Microsclere. 3. Chiaster, actines numerous, bacillary, truncate, never tylote. 
Two forms of this spicule are to be distinguished ; one, somewhat smaller than the 
other, occurs immediately beneath the investing epithelium ; it measures 0'0118 mm. in 
diameter, and presents a minute but evident centrum ; the other form is generally 
distributed throughout the sponge, it measures 0’017 mm. in diameter and presents no 
