296 
Mr. H. J. Carter’s Contributions 
the subject here is, first, to point out that the echinating spi¬ 
cule of Dictyocylindrus is the preceding grade in form to the 
more complicated one of Trikentrion —that is, while the 
former may be viewed as a single arm fixed to the fibre by an 
inflated and spined extremity (PL XXVII. fig. 14), the latter 
presents a more complicated one, in which this is effected by 
two additional divergent arms, making the spicule triradiate,— 
and, secondly, to take this opportunity of recording the descrip¬ 
tions, respectively, of two remarkable species of the genus 
illustrative of this, which were found by Col. Pyke (U.S. 
Consul) at the Mauritius, and sent to me by Dr. Dickie, late 
Professor of Botany in the College at Aberdeen, in 1872. 
For one of these I propose the name of Dictyocylindrus laci- 
niatus , and for the other D, Pykii, commencing with the 
former first. 
Dictyocylindrus laciniatus , n. sp. 
(No figures are given of this and the following species, beyond the 
echinating spicule, which is the same in both.) 
Ilemispheroidal, laciniate, radiating, sessile. Colour light 
slate-grey. Texture tender, compressible. Pores and vents 
not visible, the latter probably from their smallness, owing to 
the excretory systems in this kind of sponges being much 
subdivided. Structure consisting of long spatulate lacinite, 
radiating from a basal point, dividing and subdividing up¬ 
wards, proliferous, plicate, and slashed towards the surface ; 
composed of indistinct, anastomosing fibre, charged with the 
spicules of the species ; setigerous or hairy throughout from 
the projection of the long acuates, which will now be de¬ 
scribed. Spicules of three forms, viz.:—1, very long, seta¬ 
ceous, acuate, smooth, curved, sharp-pointed, slightly inflated, 
pin-like at the base, l-6th inch long by l-750th inch broad 
in its greatest dimensions; 2, acerate, curved, smooth, sharp- 
pointed, l-45th by l-1500th inch; 3, echinating spicule, 
short, acuate, conical, straight, inflated at the base, sub¬ 
pointed at the free extremity, spiniferous, spines most nume¬ 
rous about the extremities respectively, slightly recurved 
about the free end, l-272nd inch long by l-1500th in diameter 
at the inflated end. No. 1 is based in the indistinct fibre 
(which is chiefly formed of no. 2), and, projecting from the 
surface of the lacinia obliquely upwards, gives the latter, from 
its great length, a strongly setose character; while no. 3 
sparsely echinates the fibre. Size of specimen 2 inches in 
diameter. 
Hob. Marine, growing on hard objects. 
Loc. Mauritius. 
