TRANSACTIONS OP SECTION D. 779 



this country to gather the native woods together into one collection on a scale 

 commensurate with the extent of the new continent and the importance of its 

 forests. 



7. On the Structure and Development of Loxosoma. 

 By Sidney F. Hakmee, B.A., B.Sc. 



The nervous and excretory systems of the adult were investigated specially in 

 L. crassicauda, in the living condition or by means of glycerine preparations. 



1. The ganglion, situated between mouth and anus, has been frequently figured 

 in previous papers on Loxosoma, but has hitherto invariably been wrongly 

 identified as some part of the generative system. It is a dumb-bell shaped organ,, 

 developed in the bud from ectoderm, and giving off at its two ends nerves to the 

 tentacles and other parts of the body. The ectoderm contains numerous sense-cells, 

 bearing one or more long stiff tactile hairs projecting into the water. Each sense- 

 cell is directly connected with the nervous system by means of a single fine nerve 

 fibril, swelling into a bipolar ganglion cell at some part of its course. 



2. The excretory system consists of a pair of fine tubes, ciliated internally, and 

 composed of a small number of large perforated cells, the proximal cell being in all 

 probability a flame-cell. There is no ciliated funnel, the excretory organ ending 

 blindly near the ventral wall of the stomach. Each tube opens independently into 

 the vestibule, between mouth and anus. The nephridia of Loxosoma thus differ 

 markedly in structure from those of Brachiopoda or Phoronis, but resemble in 

 a striking manner the head kidney of Annelid larvae, as well as the permanent 

 nephridia of Rotifers and Platyhelminths. 



3. The development of Loxosoma has been studied by means of sections in a 

 species, probably hitherto undescribed, occurring en Leptodinum in the Gulf of 

 Naples. 



The ' dorsal organ ' is not developed from hypoblast cells, as stated by Hatschek 

 in Pedicellina (< Zeitschr. f. wiss. Zool./Bd. xxix. 1877, S. 502), but, on the contrary ; . 

 entirely from the epiblast. An epiblastic invagination is formed, but soon loses its 

 lumen, then appearing as a solid crescent-shaped mass of cells, applied to whose 

 deeper surface is a conspicuous mass of fibrous tissue. The ' dorsal organ' bears 

 two large eyes, and is in all probability the brain or supra-cesophageal ganglion of 

 the larva. The permanent ganglion of the adult is hence infra -oesophageal, and the 

 line between mouth and anus is ventral. 



The ' dorsal organ ' takes no part in the budding of the larva, which after a free 

 life of some hours may be seen to have developed a pair of lateral buds, one on 

 each side of the ' dorsal organ,' but at a level intermediate between this structure- 

 and the ciliated ring. The alimentary canal appears to atrophy during the budding,, 

 and it is hence probable that the larva dies after the production of two or more 

 buds. It is doubtful whether the larva ever permanently fixes itself, or whether 

 the budding takes place normally during the free life of the larva. 



4. The Entoproctous Polyzoa conform perfectly in structure to the Trochosphcere 

 type. This view is much strengthened by the study of their excretory organs. The 

 results of the present investigation seem to show that the Polyzoa have their 

 nearest adult allies in the Ltotifera, whilst they have but little in common with 

 Brachiopoda or Phoronis. 



8. On Anatomical Variations: (1.) Par-occipital Process occurring in Man, 

 (2.) Secondary Astragalus. (3.) Persistence of the Left Duct of Ouvier 

 in Man. By Professor Shepherd, M.J). 



1. Par-occipital Process in Man.— The skull of an Irish navvy, aged about 

 thirty years, was exhibited, in which there was a well-marked par-occipital process.. 

 Left jugular process of occipital bone, prolonged downwards to articulate with 

 the transverse process of atlas, length, 2 cm. ; diameter, 1 cm. In the same skull, 

 on same side, the styloid hyoid ligament was ossified and articulated with the hyoid 

 bone — length, 6-2 cm. ; diameter, 3 cm. 



