NICOLEA VENUSTULA. 155 



consider it to be the same form as Dalyell's T. maculata, The bristles are winged, and 

 the hook figured resembles that of a Nicolea. 



Marenzeller in a later paper (1890) included Nicolea arctica, Malmgren, and 

 N. zostericola, Grube, under this species, and he found occasionally only fifteen bristle- 

 bundles in some typical representatives. 



De St. Joseph (1894) gives the colour as brick-red, and he notes that Michaelsen 

 found it also at Kiel. The oesophagus extends to the ninth setigerous segment, the 

 glandular stomach to the sixteenth, the " chitinous " stomach to the first abdominal 

 segment, and then the intestine ends at the tip of the body. Gregarines occurred in the 

 intestine, and two encysted Distomes similar to those in Nerine longirostris were present 

 in the coelom. This author subsequently (1906) mentions the occurrence of JJlvinia 

 ellijptica, Ming, (which Siedlecki found in Terebella nebulosa,), 1 also of Selenidium costatum. 

 Both occur in P. nebulosa. 



Ssolowiew (1899) includes, after Levinsen and Marenzeller, N. zostericola and 

 N arctica as synonyms of this species. 



Leschke 2 (1902) alludes to the larval form as first mentioned at Kiel by Willemoes- 

 Suhm. The species is ripe from April to June. The earliest larvse are found on the 

 sea-grass, and have three bristled segments in front and three naked posteriorly. The 

 colour is ochreous. Eudiments of the tentacles appear, and bristles on all the segments, 

 and it forms a mucous tube. The development is similar to that of Terebella nebulosa as 

 described by Milne Edwards. 



Southern's (1914) examples from Clare Island all had seventeen pairs of bristles. 



Dr. Allen and Mr. Crawshay, from their observations at Plymouth, consider Nicolea 

 venustula, Mont., distinct from N. zostericola, (Erst, and Grube, and the former kindly sent 

 the type-specimens for examination. In glancing at them it is apparent that the sizes of 

 the two forms differ, but whether this is due to race or to age is unknown, both being 

 mature. The first pair of branchiae in N. venustula form a much denser arbuscle than in 

 N. zostericola, but the branchia3 of the latter vary amongst themselves and the differences 

 may be due to age. N. zostericola has fifteen pairs of bristles as a rule, N. venustula has 

 seventeen pairs, yet Prof. Fauvel has found the latter with only fifteen pairs. In both 

 the males have the cirrus over the third and fourth bristle-tufts, and in these examples the 

 cirri were more conspicuous in N. zostericola, but this is a variable character. There is 

 nothing else distinctive in external appearance. Both have bristles of the same structure, 

 N zostericola, the smaller form, having paler shafts and tips, but precisely the same slight 

 bend and the same narrow wings on the finely tapered extremities, which seem to be of 

 similar proportions in each. The hooks of N. zostericola are also alternately arranged in 

 the rows, and each has a dorsal outline nearly straight till it reaches the projection at the 

 base, this projection or heel being more distinct in the Norwegian forms, the outline of 

 the latter in the normal position sloping downward and forward to a smoothly rounded 

 prow, whilst the anterior outline has a process for a ligament about its middle, the 

 concave curve on each side of this being nearly symmetrical, viz., upwards to the main 

 fang and downward to the prow. Most of the hooks present only a single tooth in 



1 < Ann. Instit. Pasteur/ July, 1903, p. 430, pi. viii, figs. 1 and 2. 



2 ' Wiss. Meeresuntersuch./ Bd. v, p. 127. 



