524 



SCIENCE. 



[Vol. VIII., No. 200 



CHALLENGER REPORTS. 



The number of species collected by the Chal- 

 lenger in the group Marseniadae was but three, 

 two of which, however, belong to a new genus. 

 Dr. Rudolph Bergh, who is monographing this 

 lamiiy, has not only given very full accounts of 

 the anatomy of the species collected, but has 

 added to them a general history of the nomencla- 

 ture of the family, a list of the known genera and 

 species, notes on their gergraphical distribution, 

 and other matter of importance. He regards the 

 group as most nearly related to the Velutinidae, 

 and even suggests that a more thorough knowl- 

 edge of both families may render it necessary to 

 consolidate them. 



The report on the Scaphopoda (tooth-shells) 

 and Gasteropoda, by Eev. Robert Boog Watson, 

 exhibits a stupendous amount of labor. It is ac- 

 companied by an appendix in which the Marquis 

 de Folin reports on theCaecidae, a group of minute 

 and interesting shells. The collection included 

 some 1,300 recognizable species, new and old, with 

 some 400 undeterminable fragments or worn 

 specimens. Shore-collections furnished 86 species, 

 of which 7 were new. Dredgiog-stations to 400 

 fathoms yielded 604 old species and 405 new ones. 

 From forty-one stations between 2,650 and 400 

 fathoms, 89 known and 1B5 previously unknown 

 species were obtained. The greatest depth at 

 which any gastropod was secured was 2,650 

 fathoms, at station 325. Here a Stilifer, parasitic 

 on some echinoderm, was obtained. Basilissa, 

 Dentalium, and Trochus were found in 1,900 

 fathoms ; Dentalium, Cithna, and various Pleuro- 

 tomas were found in between 3,000 and 2,500 

 fathoms ; and the large and interesting Guivillea 

 alabastrina was dredged off the Crozets in 1,600 

 fathoms. Oocorys, Fusus, Cadulus, Seguenzia, 

 Cylichna, and Actaeonare among the genera which 

 presented themselves most frequently from the 

 abysses. Leaving the shallow waters out of ac- 

 count, perhaps the richest haul of the voyage for 

 the conchologists was that in 390 fathoms, off 

 Culebra Island in the West Indies. This produced 

 about 150 species, of which only about ten per 

 cent were previously known to science. The aver- 

 age number of species of moUusks collected at 

 a station was less than twelve. Mr. Watson's 

 introduction is short. He lays stress on the im- 

 portance to molluscan life of temperature ; to a 

 less degree, of depth ; great differences in these 

 respects operating as barriers against dispersion. 

 He notes the importance of time in affording op- 

 portunities for distribution ; so that species which 



Report of the scientific results of the voyaqe of the Chal- 

 lenger during 1873-76 Vol. xv. : Zoology. Loudon, Govern- 

 ment, 1886. f°. 



are found fossil and still exist, being presumably 

 ancient, may be expected to occur over wide 

 geographical areas. Where barriers of depth and 

 temperature do not check distribution, the species 

 tend to become universal, and in some cases have 

 attained universal distribution. Finally, Mr. Wat- 

 son affirms that ev en in the oldest and most widely 

 distributed forms there is no trace of essential, 

 lasting, and progressive change. This assertion 

 may well be accepted, for it is precisely among 

 such ancient and universally distributed forms 

 that we should expect those evidences of inflexi- 

 bility which have been recognized as characteris- 

 tic of certain species by naturalists from Darwin 

 down. It is the local and restricted species which 

 should be studied for evidences of change. Where 

 each pond has its form of Limnaea, and each tree 

 its Clauailia or its Achatinella, there should evi- 

 dences of change or adaptation be most easily 

 recognized. Every one who has occasion to deal 

 with deep-sea mollusks will find the learned, pains- 

 taking, voluminous, and profusely illustrated re- 

 port of Mr. Watson an absolute necessity ; and for 

 other malacologists it will be, not a mine, but 

 rather a warehouse of elaborated and systema- 

 tized information. 



The number of chitons collected by the expe- 

 dition was small, as they are chiefly littoral in 

 habit. There are reported on by Professor A. C, 

 Haddon some thirty species of fifteen genera, of 

 which seven were previously undescribed, and 

 others, though described, had not been figured. 

 The really deep-sea chitons all belong to the genus 

 Leptochiton, and, judging by their sculpture, are 

 nearly related forms. Leptochiton Belknapi, Dall, 

 was dredged in over one thousand fathoms near the 

 Aleutian Islands by the U.S.S. Tuscarora, and by 

 the Challenger in about the same depth off the 

 Philippine Islands. An allied species (L. ben- 

 thus. Had.) was found in twenty-three hundred 

 fathoms in the North Pacific, nine hundred miles 

 north of the Sandwich Islands. It is so far the 

 most abyssal chiton known. In all these cases the 

 temperature was low, not exceeding 37° F. The 

 genus, as one might expect, appears in shallower 

 water toward the poles. Professor Haddon gives 

 a synopsis of Carpenter's classification, and of the 

 genera of Leptoidea. In his discussion of the 

 species, he gives a valuable resume oi the status of 

 the genera, and proves beyond question that the 

 genus generally known as Chitonellus must be re- 

 feiTed to Cryptoplax, Blainville, the various sub- 

 divisions resting upon insufficient or erroneous 

 figures and observations. The plates to Professor 

 Haddon's memoir are particularly excellent, and 

 the paper marks a distinct step in advance in our 

 knowledge of this very interesting group. 



