TKTKA.\tXII.\ 27 



Echinating acanthostyles, 219 x 18'75/j (without including spines), larger spines 

 situated on the head 9 /< long. 



\.- ' nial ainpli it ylrs, :!.">(; I I .. -: MI- :i raj dightly fusiforn ibtylot*- ind 

 with a small uiucru at each end. 



Mi. ros. Im-s, none 



Myjcillti victorutwt Dcndy (Ifalicltondria pushtlosa Carter), (5. p. 30), would come 

 under this genus, although, at the same time, it is in possession of isochelac, and the 

 heads of the styli of the main fibres occasionally have a slight indication of spination 



Two fragments (No. 123) were dredged off Coulman Island in 100 fins. A third 

 specimen (No. 38) on Horn/era was obtained from east end of Barrier, 100 fins., l>ottorn 

 mud, stones, and rocks. 



II. SUB-FAMILY MYCALINAE, THIKLK. 

 I. GROUP MYXILLKAK, LUNDBKCK. 



MYXILLA DKCKPTA. 



(Plate XXII., figs. l-2a, and Plate XXV., fig. 3a-) 

 1907. Mynlla dettpta Kirkpatrick (lOa. p. 278.) 



Description. 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 vertically 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 couulcs 

 supported by acanthostyles. The colour of lx>th specimens is reddish brown. 



The skeleton in the very thin incrustation, at first sight, resembles that of a 

 Hymerrhaphia ; each vertical acanthostyle is isolated, and with its head on the base 

 and its pointed end projecting.* In the thicker specimen it is possible to make out 

 primary and secondary lines of skeletal fibres. 



The cctosomal spicules are partly arranged in paniculate tufts, partly lying 

 tangeutially in the dermal membrane. 



Spicules. MflflMileim Choanosomal acanthostyles, 4G8 x 23*5/i, curved, 

 spined at the head only, with sul>-tornote points. Ectosomal strongyles 238 x 4 6 /*, 

 straight, smooth, cylindrical, usually with a pointed mucro at one end. 



Microscleres. Arcuate isochelse, 19'5/i long, 5'G/i broad, palmate tooth 8 ft long 

 ovoid, with rounded distal edge ; with thick curved shaft ; with tongue-shaped ale 

 about 8 fi long. 



Isancorse uiiguiferae, 15'3/z long, with slender, curved, sometimes wavy shaft, 

 with three sharp claw-like teeth at each end. 



Chelate bipocilla 8 /* long, with deeply curved shaft with spathulate ends each 

 with three triangular denticles ; these spicules are fairly common and not accidental. 



