Mr. J. Alder on new species of Sertularian Zoophytes. 353 



figure of the organization of a Cestoid is given, which corresponds 

 with plate B in the treatise published by the Academy of Brus- 

 sels in 1850; and by the side of it a similar ideal figure of a 

 Trematode is now added. The work deserves to be perused and 

 studied, and must always be recorded with honour amongst the 

 zoological and anatomical literature of our age. 



[This notice, by the Leyden Professor of Zoology, is translated from the 

 ' Nederlandsch Tijdsehrift voor Geneeskunde,' 1859.] 



XXXVI. — Descriptions of three new species of Sertularian Zoo- 

 phytes. By Joshua Alder, Esq. 



[With three Plates.] 



Plumularia halecioides. PL XII. 



Polypary about an inch high, irregularly branched. Stem 

 compound, giving off branches, which are also compound for a 

 part of their length, becoming single as they rise upwards, and 

 having two joints above the insertion of each branchlet or pinna ; 

 pinnse alternate, frequently short, terminating in a single cell, 

 but in full-grown and luxuriant specimens extending to a greater 

 length, and bearing three or four rather distant, moderately 

 sized, cup -formed cells on the upper side. There are two, or 

 occasionally three, joints at the origin of each pinna, as well as 

 between the cells, and a small tubule above and another below 

 each cell. Sometimes there is a tubule on the stem above the 

 origin of the pinna. The polypes are rather large in proportion 

 to the cell, rising a little out of it, and having from fourteen to 

 eighteen muricated tentacles. The ovicapsules are large, ovate, 

 with a broad truncated top, and are strongly ribbed or wrinkled 

 transversely ; they are set on the stem singly or in clusters by a 

 very short pedicle. 



I found two specimens of this very distinct and beautiful little 

 Plumularia on stones near low-water mark, at Cullercoats, North- 

 umberland, in the summer of 1857, and again met with it at 

 the same place in the following year. Mr. Albany Hancock has 

 also obtained it at Roker, on the Durham coast. In its young 

 state, or when partially denuded of its cells, it has very much the 

 appearance of a Halecium, which genus it resembles in its mode 

 of growth. The ovicapsules are similar to those of Campanularia 

 Johnstoni — the only instance within my knowledge of this form 

 of capsule being found in a Plumularia. Pressed between plates 

 of glass, the capsules showed the ova in a very early stage. I 

 unfortunately did not succeed in keeping the specimens alive so 

 as to observe their further development. 



Ann. ^ Mag. N, Hist. Ser. 3. Vol. iii. 23 



