STYLASTERIDAE jr 



The female gonophore in its fundamental features is constructed as in Stylastct gemmasccus. 

 But its spadix is simpler in structure (PL V figs. 47 and 48); it is bowl-shaped. Whilst the spadix 

 in Stylaster gciiunascciis develops blind sacs in the direction towards the central parts of the ."ono- 

 phore, all the blind sacs in Stylaster rosnts lie along the periphery of the gonophore. The structure 

 may here be said to be more primitive than in Stylaster gcinmascens. 



The synonymy of the species is not easily determined with certainty from the literature. No 

 differences between the available colonies and the old descriptions of Stylaster roseiis can be found. 

 As the species is the commonest Stylasterid in the Atlantic north of the equator, it is ])robabl\- the 

 same form that served as a basis for Pallas' description of J\/adrepora rosea] the name also agrees with 

 the colour as noted by the collectors of the present material. The only disagreement to be noticed 

 between these colonies and Milne-Edwards' description (1857 p. 130) is, that the small branches 

 seldom show coalescences; but this character is of little importance and can scarcely be con.sidered 

 sufficient as a specific distinction. Pourtales (187 1 p. 34) under the name of Stylaster erubescens 

 describes a species from the deeper lasers at Florida; his excellent figures show at once, that it can- 

 not be specifically distinct from the North Atlantic Stylaster roseus] on the other hand, it is exceedingly 

 doubtful if it is this species which he (1. c. p. 83) with doubt refers to Pallas' species as Stylaster 

 rose/is. P. M. Duncan (1874 PI. 49 fig.s. 13 — 15) figures the species from the Faeroe Channel, but refers 

 it erroneously to Stylaster geiin/iaseciis. Stylaster roseus is common in the northern Atlantic south of 

 the submarine ridge between Scotland— Iceland and Greenland. 



Subgenus AUopora (Ehrenberg) 

 Stylaster norvegicus (Gunner us) 



1768 Millepora norvegica^ Guunerus, Om uogle norske Coraller p. 64, Tab. II figs. 20 — 22. 



1873 AUopora norvegica, G. O. Sars, Dyrelivet paa vore Havbanker p. 45. 



1874 Stylaster gemmascens pars, P. M. Duncan, Madreporaria . . . "Porcupine" p. 332, PI. 49 figs, i — 3. 



1881 AUopora oculina, Moseley, Stylasteridae, "Challenger" p. 85. 



1882 — norvegica^ Storm, Bidrag til Kundskab oni Trondhjemsfjordens Fauna, IV, p. 26. 



1888 — oadina + A. norvegica, Hicksou, On the maturation of the ovum and Development of 

 AUopora p. 595. 



The fan-shaped colonies are generally branched in one plane; they are not recurved and show 

 no distinct division into stem and branches. The cyclosystems are arranged irregularly; the)- are most 

 numerous on the front surface of the colony. They are circular or more rarely somewhat oval and 

 have from 5 to 9, in general 6—7 quite separate dactylopores, each with a faintl>- developed dactylo- 

 style. By means of a shallow incision the gasteropore stands in communication with the dactylopore. 

 The gasterostyle is approximately spherical, of the same height as breadth. The gasterozooid has 

 from 5 to 7, in most cases 6 quite small tentacles. — The ampullae are deeply imbedded and are hardly 

 seen on the surface of the colony. The male ampullae contain in general 3, seldom 2 or 4 gonophores. 

 The surface of the colony is smooth, not reticulated. ' / . ' 



