Report on the zoological collections made in the Indo-Pacific Ocean ...

ALCrONARIA. 359? Mt5lit^e ochrac^e, De Blainville, 3Ian. Actinol. p. 604, pi. Ixxxvi.fig. 3.P Mopsella retifera, Studer, MB. Ah. Berlin, 1878, p. 666.Lamarck's species seems not to have been clearly identified bymodern writers, with, perhaps, the exception of Verrill (Bull. Mus.Comp. Zool. Camb. i. p, 38) ; I have, however, little doubt of itsidentity with a form which occurs somewhat abundantly in thiscollection from Port Molle, Queensland, &o. I have thought it wellto describe this form fully, in order to clear up the uncertainty whichhas hitherto prevailed as to the correct name of the species.It branches strictly in one plane and has elongated meshes ; thestem and main branches are slight and break up almost immediatehjinto a reticulum of undulating thin branchlets, which almost allanastomose ; the terminal branchlets are only, about 1 millim. indiameter. The internodes are long ; the joints are small, short, andsquarish. The cortex is rough, rather dull scarlet ; the zooidverructeof the same colour ; the expanded zooids, scarlet in onespecimen, yellow in another, are equal and small, but distinctly prominent,abundant over the front and sides of the branches. Axisof joints firm, bright red, that of basal internodes longitudinallychannelled, deep red ; of distal internodes faintly striated, but otthe same tint, and penetrated bj^ the longitudinal canals.Spicules of general cortex Fusiform, sharply pointed at both:—(i.)ends, as a rule, and covered with irregularly scattered tabercles,which are large and blunt at the middle of the spicule, minuteat the ends ; dimensions '18 by '035 millim. (ii.) " Blattkeulen,"large, either with long cylindrical shaft, strongly tuberculate, withlarge compound tubei'cles and two " leaves " which are broad,rounded, the edges divided into blunt teeth, or with the shaft moreor less aborted : dimensions of spicule '21 by '105 millim., length ofcylindrical shaft alone about •! millim. Spicules of verrucoe :—(iii.)Longitudinal, curved, fusiform, tapering gracefully to sharp points,with rather few tubercles, prominent and sharp at middle, disappearingtowards ends ; dimensions -24 by •035 millim. (iv.) Horizontal,very regularly fusiform, curved, pointed rather bluntly,covered with very closely set, low, blunt tubercles ; dimensions '28by '041 millim.Bah. Port Curtis, 5-7 fms. ; Port Molle, 12-20 fms. ; ThursdayIsland and Prince of Wales Channel, Torres Straits, 4-7 fms. Also,perhaps. Dirk Hartog Island, W. Australia, and N.W. AustraliaIStnder).This is a delicate and graceful species ; it is represented in thiscollection by two nearly perfect specimens and a number of fragmentsin the dry state, and by a specimen and fragments in spirit. Thelargest specimen measures 193 millim. (nearly 8 inches) in height,by 140 millim. (6 inches) in maximum breadth; the thickness ofthe base is—^joints 6 millim., internodes 4 millim. Lamarck's andLamouroux's descriptions suit the species very well, and the remarkof the latter to the effect that it is " peu rameuse ; se divisant subitementeu ramuscules tros-menus, filiformes, verruqucux, anastomoses,"