REPORT ON THE TETRACTINELLIDA. 
341 
Macandrewia clavatella (0. Sclimidt). 
Corallistes clavatella, 0. Sclimidt, Spong. Atlant. Gebiet., p. 23, pi. iii. fig. 7, 1870. 
Macandrewia azorica, Carter, Ann. and Mag. Nat. Hist., ser. 4, vol. xii. p. 438, 1873 ; vol. xviii. 
p. 464, 1876. 
,, clavatella, Zittel, Abhandl. d. k. baier. Akad. d. Wiss., Bd. i. pp. 39, 57, pi. i. 
fig. 3, 1878. 
Discodermia clavatella, 0. Sclimidt, Spong. Meerb. Mexico, p. 24, pi. iii. figs. 2, 3, 5, 1879. 
SjMiige. — Obconic, seated on a short pedicel, attached, summit flattened or depressed, 
or convexly rounded, bearing several oscules, 0'25 to 1‘0 mm. in diameter, with margins 
slightly elevated or not ; or incrusting. General arrangement of the excurrent and 
incurrent canals as in Jerea. Pores 0'035 to 0’04 mm. in diameter, dispersed over th^ 
sides of the sponge, margins furnished with a fringe of microxeas which radiate up to the 
centre of the pore. 
Spicules.- — I. Megascleres. 1. Desma, protocladi usually smooth, about 0'05 by O'OlO 
mm. to 0‘1 by 0 ‘01 4 mm., syzygial tubercles short, well rounded ; axial rod of crepis 
from 0‘0276 to 0'036 mm. in length. 2. Oxea, fusiform, slender, 0’39 by 0‘013 mm. 3. 
Pliyllotriwne, rhabdome and cladi each 0‘13 in length ; the axial fibre which extends 
throughout the rhabdome does not proceed much beyond 0'015 mm. into the cladi. 
II. Microsclere. 4. Microxea, fusiform, sometimes with an ellipsoidal centrotylus, 
usually curved, 0'055 by 0’004 mm. The microxeas form a single layer beneath the outer 
epithelium, fringe the pores, and extend throughout the sponge. 
Colour. — Greyish-white. 
Habitat. — Florida; depth, 152 to 270 fathoms (Pourtales, 0. Schmidt). Gulf of 
Mexico; depth, 131 fathoms (Agassiz, 0. Schmidt, Stations 203, 210). 
Remarks. — This species appears to me to be very clearly distinguished from Macan- 
drewia azorica, Gray, with which Carter has identified it. ISiot only is the general form 
not the same, but the arrangement of the excurrent and incurrent canals, and the 
characters of the desmas, differ markedly. In Macandrewia azorica the syzygial spines 
are more or less conical, and tend to run out into long slender processes — Carter has 
compared them to the antlers of deer, — but in Macandreivia clavatella they are short and 
well rounded, and have no tendency to elongated growths. 
0. Schmidt regards the desma as tetracrepid, since in some cases it presents a tetrac- 
tinate axis, one of the actinal fibres being very long as compared to the other three ; at 
the same time he states that it is also frequently monocrepid, and hence concludes that 
the sponge presents evidence of a passage from the Tetracladine to the Rhizomorina 
type ; at the same time, regarding the characters of the discotrioene as of more import- 
ance than those of the desma, he assigns the sponge to the Discodermia group of the 
Tetracladina. An examination of one of the Mexican specimens on which Schmidt bases 
these statements enables me to confirm his observations in the fullest manner. The desmas 
