TRANSACTIONS OF THE SECTIONS. 143 



DlCOHYNB. 



Gen. Char. — Coenosarc branched, clothed with a polypary and adhering by a 

 tubular network. Polypes claviform, of two kinds, one sterile, the other proliferous, 

 both borne upon the common coenosarc, and issuing from the extremities of the 

 branches. Sterile polype3 with a verticil of tentacula situated behind the mouth; 

 proliferous polypes destitute of tentacula (and mouth ?), and having the gonophores 

 clustered round their base. 



D. stricta. — Stem rising to the height of about \ an inch, irregularly branched ; 

 branches ascending at a very acute angle from the stem. Polypary slightly dilated 

 at the extremities of the branches, somewhat corrugated near the base, but without 

 distinct annulations. Tentacula about 16 in a slightly alternating verticil. 



On Laomedea tenuis, n. sp. By Professor Allman, M.D., F.R.S. 



This new species of Laomedea was obtained by the author while dredging in the 

 Orkney seas, and was now described with the following diagnosis : — 



Stem geniculate ; polypiferous ramuli having the same diameter as the stem, 

 springing alternately from the geniculations ; the entire stem and ramuli distinctly 

 annulated; polype-cells with deeply-cleft margins; polypes very extensile, with 16 

 or 18 tentacula. Capsules medusiferous, large, cylindrical, with the proximal end 

 conical, and with the remote end broad and truncated. 



On a remarkable Form of Parasitism among the Pycnogonidae. 

 By Professor Allman, M.D., F.R.S. 



The author described the occurrence on the branches of some species of Coryne, 

 of peculiar pyriform vesicles, which might at first sight be easily taken for the repro- 

 ductive sacs of the zoophyte. 



They had their cavity in free communication with the general ccenosarcal cavity of 

 the zoophyte, and an endoderm, ectoderm, and external chitinous investment were 

 easily demonstrable in their walls. 



The nature of their contents, however, at once distinguished them from the pro- 

 per reproductive sacs of the Coryne; for in every instance they enclosed a Pycno- 

 gonidan (Ammotheal). The included Pycnogonidan was always solitary, and in the 

 smaller vesicles was still embryonic, while in the larger ones it presented an advanced 

 stage of development, and was ready to escape from its confinement by the rupture 

 of the surrounding walls. 



On the Structure of the Lucernariadae. 

 By Professor Allman, M.D., F.R.S. 



In this paper the author described the structure of the Lucernaria cyathiformis of 

 Sars, which, however, differed so much from the typical Lucernaria as to convince 

 him that it ought to be placed in a distinct genus, for which he proposed the name 

 of Carduella. 



The central stomach, which the author compared to the manubrium of a gymno- 

 phlhalmous medusa, has the reproductive system developed in its walls, and eight 

 vertical septa extend from it, converging in pairs to the external walls of the body, 

 to which they are attached by four equidistant longitudinal ridges. These external 

 walls arc the exact representative of the umbrella of a medusa, and the author believed 

 that he had succeeded in demonstrating the existence in them of four equidistant 

 longitudinal canals, which run from the base of the cup-shaped body of the animal, 

 to within a short distance of its margin, where they open into a circular canal, into 

 which the tubular tentacles also open. 



Prof. Allman endeavoured to show that the structure of Carduella was essentially 

 that of a gymnophthalmous medusa, the longitudinal lamellae by which the little 

 animal might at first sight appear referable to the actinozoal type of structure being 

 totally different in their arrangement and relations from the gastro-parietal lamella 

 of an Actinia. 



We have only to conceive of a Thaumantias, or similar medusa, with its manubrium 

 united to its umbrella by the development within the latter of the eight septa just 



