12 



MARINE AND FISHERIES 



6-7 EDWARD VII., A. 1907 



appearance on July 11 (fig. 2), and a comparison of my sketches with Mortensen's 

 figures (Nordisches Plankton IX., 16) induces me to refer it to Ophioglypha, of which 

 0. rohusta ayres is the common species at Canso. My sketches, however, are not suffi- 

 cient to give an accurate picture of the form of the skeleton (Plate Y., fig. 2). Still 

 later, on July 18, (3) the first Bipinnarise of Asterias vulgaris were recorded (fig. 3). 



TBEMATODES. 



A few examples of what has been supposed to be the pelagic egg of a Trematode 

 were detected in both years; such at least, is the interpretation placed upon these by 

 Canu (Ann. de la Station Aquicol. 'de "Boulogne-sur-mer, Vol. I., pt. 2, p. 112, Plate 

 VII., fig. 8-9). The Canso specimens are longer and comparatively slenderer 290/^. 

 (of which 182 to tail) x 50, while Canu's measure 160 x 42. 



The larvsB of Hemiurus appendiculatus Hud, and Derogenes various, O. F. Miiller, 

 diagnosed by Dr. Stafford, are found occasionally free, as well as in the interior of 

 Copepods {Acartia sp. at Malpeque). 



ANNELIDA. 



Of the two families which are exquisitely pelagic in their habit, the Alciopidse 

 and the Tomopteridae, only the latter was represented in the tow-net takings at Canso, 

 and that by a single example taken out at sea in the end of August. (Plate V., fig. 

 5). Prom Apstein's account of the Tomopterids of the Plankton expedition, one 

 would have expected that it would have turned out to be T. helgolandica or T. septen- 

 trionalis, but his excellent account enables me to diagnose it as a young example of 

 T. Mariana. It measured 1.25 mm. in length, had the cephalic tenacles the two 

 pair of tentacular cirri and five pair of parapodia developed, of which the two first 

 carried yellow (phosphorescent ?) ' rosettes ' on the basal joint, while the middle line 

 of the back had some twelve distinct pink spots, which were also present on the ten- 

 tacular cirri of the parapodia. JSTo rosette was observed on the fin of the third pair 

 of parapodia. 



LARVAL FORMS. 



Before any satisfactory account can be given of these, it will be necessary to work 

 over the adult Annelids of the region. Two Spionid larvae, one of them Polydora 

 ciliata, were very common, but I propose to confine myself here to registering the 

 occurrence of some forms of particular interest. The Polygordius larva (Plate V., 

 fig. 6) was frequent in July, as was also a Mitraria larva (fig. 7), but my attention 

 was more arrested by a larva developing within an egg-membrane of peculiar character, 

 of the systematic position of which I have not been able to satisfy myself. The 

 embryo in question was first observed towards the end of July in an early stage of 

 segmentation, with a large space between it and the peculiar shell of some 225 p- in 

 diameter. On the inner surface of the latter were to be seen numerous pear-shaped 

 vesicles apparently opening to the exterior (fig. 8). Towards th end of the month a 

 single cilated band had been established and later a well-marked anterior bunch of cilia 

 as well as a posterior ring (fig. 9). 



Still later two bunches of provisional setae, some 130 /i in length, five in each 

 bunch made their appearance (fig. 10), two brown eye-spots became obvious, and two 

 caudal (sensory ?) organs were observed. The shell lost the peculiar pear-shai)ed 

 vesicles as development advanced; it was perforated by the cilia and bristles, and 

 eventually was ruptured by the escape of the larva. This I observed towards the 

 middle of September, but only detected a single example of such a free larva. 



Another developing embryo of larger size, 555//, related to the above, was also ob- 

 served less frequemtly in September. The shell lacked the vesicular structures observed 



