CERIANTHARIA. 



15 



glandular tract in the mesenteries of the ist and and cycle, and in the protomesenteries 2. Lastly, 

 Danielssen has treated the anatomy of C. borcal/s, a species that has turned out to be identical with 

 C. lloydii (see below). If that description should be regarded as correct C. horealts would be a form 

 extremely divergent from the other known Ceriantharia, to judge by everything. Dauielssen's de- 

 scription must be considered for the most part wrong. In what follows I take hardly any account 

 of that description and I do this all the more because, on reviewing the Actiuiaria described by 

 Danielssen, I have been brought to the conclusion that Dauielssen's descriptions of the anatomical 

 facts concerning these are in the highest degree untrustworthy. 



The column: Ectoderm thick with extremely numerous nematoc\sts principalh' of the kind 

 with much coiled spiral thread — the longest I measured attained 

 a length of 72 ,« and a breadth of 14/^!; but probably still longer 

 nematocysts occur. In addition there is a sprinkling of thick-walled, 

 very small nematocysts about 41 /^ long. The longitudinal muscula- 

 ture is verv strongly developed except in the most distal portion. 



The tentacles in an outstretched state with somewhat thin 

 ectoderm. The ectoderm of the outer tentacles contains nematocysts 

 which are principally spirocysts. The nematoc>-sts of the inner ten- 

 tacles agree with those of the stomatodaeum, though spirocysts are 

 quite numerous. Tne largest thick-walled ones were about 41 — 



43 ,« lo"g- 



The oral disc is hke the tentacles in structure, though the 



radial musculature is stronger. 



The stomatodaeum (Fig. 1—5, PI. 3) also shews the structure 

 characteristic of the Cerianthidae in general. The ridges are formed 

 of thickenings of the ectoderm in the highest part of the stomato- 

 daeum, in the aboral part where the ridges are considerabh- higher 

 they are supported by mesogloeal enlargements (PL 3, Fig. 2, 4). The 

 ectoderm in the upper part of the stomatodaeum contains 3 kinds 

 of thick-walled nematocysts, some being about 46— 48/j long, and broad, some about 34^ long, and 

 broad, and lastly some 19—22/^ long, but narrow. Of these the last class is the rarest, the first the 

 most numerous. In addition spirocysts are found but are not particularly numerous. The ectoderm 

 supported by mesogloeal processes is provided at the summit of the ridge with gland cells and a 

 sprinkling of nematocysts, whilst the sides of the ridges and the furrows between the ridges chiefly 

 contain supporting cells. At the bottom of the furrows and the transition to the filaments the ecto- 

 derm is more strongly ciliated than higher up (Fig. 3, PI. 3). The nematocysts in the aboral part of 

 the stomatodaeum agree with those in the oral, the large ones about 41 — 43// long, the smaller more 

 thinh- scattered than in the oral part. The longitudinal musculature of the ectoderm is feebly developed. 



The siphonoglyph (si) contains, besides supporting cells, only solitary nematocysts, but numer- 

 ous mucus cells, particularly numerous on the border towards the stomatodaeum (Fig. 5, PI. 3). An 

 ectodermal longitudinal musculature is almost entirely absent. The hyposulcns contains very numerous 



Textfig. 3. Transverse section of Ceri- 

 iiiithus lloydii in the upper part of the 

 stouiatodaeuin. For the signs see ex- 

 planation of the figures. 



