TRANSACTIONS OF THE SECTIONS. 129 



The nppaient absence oi Hi/pfricum montanum, Saxifrcif/a f/ranuhita, C'hrysosj)le- 

 nium (diernlfuUum, I'l/ruhi minor. Pinf/inada vulgaris, and about CO other species 

 found in adjoining coiuities is noteworthy. 



The species peculiar to the county are Fhytemna spicahtm, Lonicera xylostemn, 

 and Trifolium stcUaium, neither of which, bowever, is admitted, without question, 

 as being indigenous, though there can be little doubt of the first. The second, 

 Babino-ton says, is indigenous, and the last is generally considered a ballast in- 

 troduction, but it has held its gTOund for upwards of half a century. 



[Species preceded by an asterisk are not found in the adjoining coimties.] 



On some Specimens of Tortnla inelinata. Bi/ Prof. Lawson. 

 The author said that Prof Lindberg, while staying at Oxford, was good enough 

 to go throughhis collections of Mosses and correct all those that were wrongly named. 

 Amongst other mistakes, Prof Lindberg detected this specie?, which was new to the 

 Eiitish Isles, mixed up with specimens of Tortida turtuosa. Tliis specimen, Prof. 

 Lawson explained, had been gathered by himself two years ago, growing on the 

 sides of the rocks in the old stone-pits at Holton, about four miles from Oxford, 

 and bad been confounded by him with T. torfuom. lie briefly described the points 

 in which these two very closely allied species differed, and expressed an opinion, 

 founded upon its geographical distribution, that now the attention of bryologists 

 was called especially to it, it would be found elsewhere in Britain. 



On a curious Elm. By M. Moggeidge. 



This w.as an elm growing in Kensington Gardens, near the Engine House at the 

 head of the Serpentine. Its height was 55 feet and circumference 7 inches. At the 

 height of about 8 feet from the ground, above a decayed portion of the trunk, a 

 mass of aerial roots descended to the gTound without further contact with the trunk. 



ZOOLOGT. 



On the Structure and Development o/Mitraria. By Prof. Allman, F.R.S. 



Several specimens of the remarkable larval form, to which Johann Miiller gave 

 the name of Mitraria, were obtained by Prof .yimau in the Gulf of Spezzia, and 

 were made the subject of careful study of structure and development. MecznikoiF 

 had recently examined another species of the same form ; and the author was 

 enabled to confirm the main result arrived at by him, that Mitraria was tlie larval 

 form of an annelid. In some fundamental points, however, regarding the pro- 

 cess of development, his observations did not agree witli tho.se of Ihe Kussian 

 zoologist ; while in structure there are some important features which have not 

 been described by either Miiller or Mecznikofl" — diflerences which may, in some 

 cases at least, depend on actual differences between the species examined. 



The nervous system is well developed, and consists in the principal central por- 

 tion of a large quadrilateral ganglion, formed by the union of two lateral ones, and 

 situated on the summit of the transparent dome-like bodj' of which the larva 

 mainly consists. From this two very distinct chords are sent downwards, so as to 

 form a pair of commissures with two small ganglia which are situated at the 

 opposite side of the alimentarj' canal. Besides the.<:e, two other small ganglia 

 exist in the walls of the dome at the oral side of the great apical ganglion, and 

 two similar ones at the aboral side ; these send off numerous filaments, which 

 dive at once into the walls of the dome, while each sends off a long filament to the 

 region where the alimentary canal begins to bend downwards towards its aboral 

 termination. The great apical ganglion supports two sessile ocelli, with pigment 

 and lens, and two small sphencal vesicles, each containing a clear spherical cor- 

 puscle. These last the author regards as auditory capsules. 



