278 ]\Ir. R. Kirkpatrick on the Mona.ri^nelJida 



The fine specimen (no. 184) which constitutes the type of 

 tlie nev\' species is 24 cm. wide and 25*6 cm. high. 

 Locality. Winter Quarters, 28-130 fath. 



Myxilla decepta, sp. n. 



There are two very small specimens of this species : one is 

 in the form of an extremely thin incrustation on a piece of 

 rock ; the surface is pilose, owing to the projection of verti- 

 cally dressed acanthostyles, each surrounded by tufts of 

 ectosomal spicules. The other, which incrusts the branch of 

 a Polyzoon, is thicker^ and the surface here is partly smooth, 

 partly provided with minute sharp-pointed coimles supported 

 by acanthostyles. The colour of both specimens is reddish 

 brown. 



The sheleton in the very thin incrustation at first sight 

 resembles that of a Hrjmerrhapliia ; each vertical acanthostyle 

 is isolated and with its head on the base and its pointed end 

 ))rojecting. In the thicker specimen it is possible to make 

 out i)rimary and secondary lines of skeletal fibres. 



Tlie ectosomal spicules are partly arranged in paniculate 

 tufts, partly lying taiigentially in the dermal membrane. 



Sjyicules. — JMegascleres : clioanosomal acantiiostyles, 468 X 

 23"5 /x, curved, spined at the head only, with subtoruote 

 points. Ectosomal strongylcs, 238x4*6 /a, straight, smooth^ 

 cylindrical, usually with a pointed mucro at one end. 



Microscleres : arcuate isochelai, 19"5 /u, long, 5"6 /i broad, 

 palmate tooth 8 /j, long, ovoid, with rounded distal edge ; with 

 thick curved shaft; with tongue-shaped alaj about 8 ju, long. 



Isancoraj unguifera?, 15*3 /u. long, with slender, curved, 

 sometimes wavy shaft, with three sharp claw-like teeth at 

 each end. 



Chelate bipocilla 8 fi long, with deeply curved shaft with 

 spathulate ends each with three triangular denticles ; these 

 spicules are fairly common and not accidental. 



There are also several isochelaj arcuatai in which the alffi 

 and denticle are replaced at one end by a spoon-like lamella. 



The presence in Myxilla of chelate bipocilla similar in 

 many respects to those found in the new species lophon spatu- 

 latus and I. jlahello-digitatus is exceptional. In other respects 

 the spiculation is that of a typical Myxtlla. The isocliehe 

 arcuatffi, though only half the length, resemble in shape 

 those of Myxilla nobilis, R. & D., from off the Rio de la 

 Plata, and M. diyitata, R. &, D., from the Cape of Good 

 Hope. The new species, again, closely resembles Myxilla 

 iophonoideSj Swartszewsky (Mem, Soc. Nat. KiefF, xx. p. 340, 



