Mabch 12, 1909] 



SCIENCE 



437 



Molluscan Studies on Lake Ghamplain: H. F. 



Peekins, University of Vermont. 

 Some Solothurian Structures: Chaeles Lincoln 



Edwaeds, Trinity College. 



In Oucumaria frondosa I have found vestigial 

 anal teeth, well marked in specimens 1-2 mm. 

 long, one developing at the posterior termination 

 of each mid radial line just beyond the bases of the 

 last pair of pedicels and outside of the anus. 

 These anal teeth remain small and can be found 

 in a majority of the adult specimens, but are 

 never functional and hence may be regarded as 

 vestigial. In very young Holotkuria floridana I 

 have found three fan-shaped calcareous plates, 

 two lateral and one posterior, which function 

 somewhat as anal teeth, disappearing in the adult, 

 and they also are vestigial structures. 



In Guoumaria frondosa, the female has a simple, 

 eonical genital papilla, while in the male it is 

 subdivided into three to ten parts. The distal 

 portion of each part bifurcates, a genital pore 

 terminating each branch, while the proximal por- 

 tions of all parts fuse in the common base. Here- 

 tofore subdivided, or multiple, genital papillae 

 have been known only in a few Elasipoda, but I 

 have seen no record of differentiation in the form 

 of male and female genital papillae. In one Thyone 

 and two Guoumaria a genital papilla in the male 

 only has been reported. 



The Growth of Parts in the Dogfish: Wm. E. 



Kellicott, Woman's College of Baltimore. 



The weights of the brain, heart, rectal gland, 

 pancreas, spleen, liver and gonads were deter- 

 mined in a series of 315 dogfish (Mustelus oanis) , 

 including specimens from birth, weighing about 

 76 grams, up to a maximum observed weight of 

 8,434 grams. 



It was found that these organs did not grow 

 at the same rates nor at the rate of the organism 

 as a whole. These parts, except the gonads, are 

 heaviest, relative to the total weight, at birth or 

 soon thereafter and from this time onward con- 

 stantly diminish in relative weight. 



Since the parts of the organism do not grow 

 similarly, description of its growth by recording 

 total weights does not describe the actual growth 

 processes of the whole organism, but chiefly of 

 some predominating parts — in most vertebrates 

 these are the muscles and connective tissues which 

 make up roughly 75 per cent, of the total weight. 



In this indeterminately growing form all the 

 parts mentioned tend to be outgrown by the 

 muscles and supporting tissues; a condition of 

 determinate growth might be derived from this 



by the action of some mechanism for stopping the 

 growth of these tissues at such a point that the 

 brain and viscera remain competent as physiolog- 

 ical elements. 



The Criteria of Homology in the Peripheral 

 Nervous System: C. Jxjdson Hebkick, Univer- 

 sity of Chicago. 



The synonymy of the peripheral nerves of lower 

 vertebrates is in great confusion. This is largely 

 due to the fact that the exact composition of the 

 various rami (particularly of the cerebral nerves) 

 was formerly imperfectly known, and hence nerves 

 of very diverse composition were often compared 

 on the strength merely of topographic similarities 

 of distribution. With the extension of our knowl- 

 edge of the nerve components of representative 

 vertebrates, it becomes desirable that a standard 

 method of procedure be established in the deter- 

 mination of homologies and in the selection of 

 names for mixed rami and in other cases in which 

 diversity of usage has arisen. A few rules gov- 

 erning homologies are suggested in the present 

 paper, which will be published in the Journal of 

 Gomparative Neurology and Psychology. 

 On a New Species of Goilin Shark {Scapanorhyn- 

 chus jordcmi) from Japan: L. Hussakof, Amer- 

 ican Museum of Natural History. 

 Scapanorhynchus {Mitsukurina) is a rare 

 shark occasionally taken in the deeper waters of 

 Japan. Only one species has hitherto been known, 

 S. owstoni Jordan. In the present paper a second 

 species was described, for which the name S. jor- 

 dani was proposed. It differs from owstoni in 

 the much lesser protrusibility of the jaw, much 

 smaller spiracle, smaller gill area and the more 

 forward position of the nostril, eye and spiracle. 

 The proper generic name of this shark was 

 discussed. The fish was originally described by 

 Jordan under the name Mitsukurina; but this 

 genus, as has been pointed out by several investi- 

 gators, is apparently identical with the Cretaceous 

 form Scapanorhynchus. The latter name has 

 priority. 



Some Features of the Development of Desmo- 

 gnathus fusca: W. A. Hilton, Cornell Univer- 

 sity. 

 Tactile Reactions and Polarity in Tentacles of 

 Aetinians: H. W. Rand, Harvard University. 

 The following demonstrations were exhibited: 

 Specimens of the Partulce of the Society Islands, 

 Illustrating Distribution and Isolation: H. E. 

 Cbampton. 

 Races of Paramecium and their Relation to Selec- 

 tion and Gonjugation: H. S. Jennings. 



