REPORT ON THE TETRACTINELLIDA. 
309 
0‘032 mm., the protocladi 0‘05 mm., the deuterocladi 0’223 mm. in length. In one 
instance a dichotrisene entansfled in the skeleton was observed with tuberculated cladi. 
O 
Habitat. — Coast of Portuaral. 
O 
Deep water off Madeira, Johnson; near Cape St Vincent, 374 fathoms, “Porcupine” 
Expedition (Carter). 
Remarks . — Zittel regards CoralUstes howerhanki, Johnson, and Corallistes typus, 0. 
Schmidt, as identical species ; the difference by which they are most readily distinguished 
is the size of the dichotrisene, the rhabdome of which has in Corallistes howerhanki twice 
or three times the length of that in Corallistes typus. In this respect the former species 
more closely resembles Corallistes masoni, from which it is distinguished by the far 
greater thickness of its sponge wall, as w’ell as by the characters of the desmas. 
Genus 2. Callipelta, n. gen. 
CoraUistidse in which the ectosomal megasclere has the form of a discotrisene, but 
the axis of a rhabdus. The microsclere is an amphiaster. 
Callipelta ornata^ n. sp. (PI. XXXVIII. figs. 28-30). 
Sponge. — At an early stage hemispherical, bearing a single oscule at the end of a 
tubular prolongation ; attached. 
Spicules . — I. Megascleres. 1. Desma, of the usual Corallistes-ioxm, bearing tubercles 
with cylindrical necks and expanded heads, subdivided into a few large, rounded, 
secondary tubercles ; crepidial axis, centrotylote, 0'02 mm. long. 
2. Discostrongyle (PI. XXXVIII. figs. 28, 29), rhabdome short, stout, conical, 
strongylate, frequently produced into a few conical, rounded tubercles, or branching 
lamellar outgrowths at the strongylate end, expanding distally into a horizontal disc, 
with an incised, somewhat crenate or bicrenate margin, and tuberculate distal surface. 
The tubercles are of a rounded, conical form, scattered at about equal distances apart. 
The discs partly overlap, partly are articulated together by their denticulated margins. 
Ehabdome 0’028 to 0'045 by 0’016 to 0‘02 mm., from 0'008 to 0‘012 mm. thick at the 
strongylate end, disc OT by 0T4 to OTl by 0T8 mm. in breadth and width, 0'012 mm. 
thick, tubercles about 0'008 mm. apart. 
3. Oxea, slender, cylindrical, over 0T6 mm. long by 0‘002 mm. in diameter. 
II. Microscleres. 4. Amphiaster (PI. XXXVIII. fig. 30), axis short, straight, 
cylindrical, with a whorl of spines at each end, and also at each end a single spine 
prolonging the direction of the axis ; occasionally spirally arranged spines appear on 
1 This is named Carallistes callipelta on the legend to the Plate. 
