716 ME. L. A. BOEKAJJAILE 0:S THE SPAAVN [DeC. 17, 



Several of these spawn-masses were brought in a vessel of water 

 to the rest-house at Kankesanturai, where, when they had been 

 placed in shallow glass dishes, a number of larviie hatched out of 

 them and passed through the successive stages of their develop- 

 ment until, as I was on the point of leaving for the south of the 

 island, the observations were unfortunately broken off. The 

 progress of the larvae was, however, so rapid that, starting as 

 spherical ciliated objects, they had, in the few days during which 

 they were under observation, assumed a completely worm-like 

 appearance. Their history, which I propose to describe in as 

 great detail as my information will allow ', shows an interesting 

 feature in the secretion by the larv;e, after they have for some 

 time been free-swimming, of a second mucous matrix, in which 

 they live gregariously, much as some caterpillars do in the web 

 which they spin. 



1. The youngest embryo observed (PI. XXXIX. fig. 3) was very 

 nearly spherical in shape, about "2 mm. in diameter, without eye- 

 spots or cilia, and almost filled with a mass — presumably endo- 

 dermal — of protoplasm containing yolky granules and droplets. 

 Viewed with reflected light, this mass was yellow \^'hile the outer 

 layer was white. The whole was enclosed in a thick radially- 

 striated nieuibrane. 



2. To these succeeds a stage (PI. XXXIX. fig. 4) in which the 

 young, while still enclosed in the spawn-mass, develop two eye- 

 spots in the anterior half of the sphere and a complete covering of 

 cilia, by means of which they rotate in the mucus. The cuticle 

 is thinner and its striation is less obvious. This " atrochal " or 

 " holotrochal " stage resembles the pedagic larva described by 

 Krohn and Schneider (5) as probably belonging to a Eunicid. 

 The body of the latter larva, however, was more elongate, and 

 the apical tuft longer. 



3. At the hatching-stage the .young larva (PL XXXIX. fig. 5) 

 is oval, with a broad anterior end and a somewhat narrower hinder 

 end. Round its middle is a broad ciliated band, separated by a 

 narrow g:ip from a tuft of longer cilia at the apical pole and by 

 a wider gap from a patch of medium length at the hinder end. 

 These are the characters of Haecker's " Prototrochophora," which 

 thus follows an atrochal stnge in the present instance. In front, 

 just within the anterior boundary of the ciliated baud, is on each 

 side a conical black eye-spot, with the apex of the cone directed 

 backwards and inwai'ds and its base hollowed for the reception of 

 the — as yet indistijict — refractive body. The greater part of the 

 inteinor of the body is filled by a yolky mass — the rudiment of the 

 future mid-gut, — but at each end is a clearer granular area. The 

 mid-gut rudiment projects backwards in the axial line towards 

 the anal region, with Avhich it seems to be already in connection 

 by a narrow non-yolky passage, although, as no outward opening 



. ^ The same accident which deprived me of specimens of the adult worm 

 haying also destroyed my preserved material of the developmental stages, I am 

 unable to deal with any but the outward features of the young and those 

 which may be seen, when they are mounted whole, as transparent objects. 



