OCR Text |
Show 176 MESSRS. L. MURBACn AND C. SHEARER ON [June 16, of the greatest regularity in the arrangement of the diverticula, exactly opposite one another. As a matter of fact, this opposite character arises only from a crude manner of representation. Probably this kind of symmetry is as little marked in them as in P. penicillata or P. minuta ; for these reasons in future this character should be omitted from the generic diagnosis. Fewkes (14) draws the diverticula in his species opposite, yet identifies it with P. penicillata of Agassiz. Our specimens approach the species of Fewkes more than they do the original descriptions given by Agassiz for this same species. Agassiz (2) obtained P. penicillata in the region of Puget Sound, and also on the coast as far south as the Harbour of San Francisco, where he found it very abundant; Fewkes collected his examples at Santa Barbara and Santa Cruz on the southern coast of California. H e does not doubt that these southern examples belong to the same species Agassiz described as P. penicillata from a more northern range. As already stated, this revised version of P. penicillata by Fewkes approaches very closely P. minuta ; in fact we have only ventured to give it separate specific rank on account of size, a feature of no very great importance. W e only attach importance to it here because our form was evidently mature, the great development of the gonads, the number and length of tentacles making this almost certain. Yet the height of the bell is 15 m m . in P. minuta, as compared with 40 or 50 m m. in the P. penicillata of Agassiz and Fewkes. While Fewkes identifies his species with that of Agassiz, as already stated, if his drawings and descriptions are accurate there would seem to be striking differences between the two. Some of these are the shape of the bell, which is broader, a less developed condition of the diverticula on the ends of the radial canals next the circular canal of the bell-margin, the club-shaped even branched ends of these diverticula, the position of the gonads on the part of the radial canals descending to the stomach, while Agassiz (2) states they are " attached at the highest point of the four chymiferous tubes." Agassiz figures four gonads in each group, and these reach halfway to the velum; Fewkes figures eight, and these reach almost to the level of the velum. Although Agassiz only figured four gonads, Fewkes says he subsequently found their number to be much greater. W e should hesitate, however, in emphasising these distinctions, for Fewkes, as assistant to Prof. Agassiz, had doubtless ample opportunity of referring to the original specimens and notes of Agassiz. Agassiz considers his species to be the same as that described by Eschscholtz (11) under the name of Melicertum penicillatum, p. 106. Eschscholtz gives a very short description and poor figure, from which it is hard to determine anything exact. It was found by Eschscholtz on the coast of California. Haeckel (18) follows Agassiz in arranging this species under P. penicillata, |