1899] FRESH FACTS 216 
Sexual DrmorpHisM IN Jurassic Nautini. G. C. Crick. “ Description 
of new or imperfectly known species of Vautilus from the Inferior Oolite, pre- 
served in the British Museum (Natural History),” Proc. Malacol, Soe. iii. pp. 
117-139, Dec. 1898. The observations of Willey on sexual dimorphism in the 
recent Nautilus have satisfactorily dispelled any doubts as to the existence 
of such a character, and divergences between individuals of any fossil species 
may therefore be interpreted as due to sex. Of the eleven species here de- 
scribed, seven appear to present both a broader form (male) and a narrower 
form (female) occurring at the same locality and horizon. In some specimens 
also it has been possible to trace very clearly the position of the anterior 
boundary of the muscular attachment. A specimen of V. bradfordensis shows 
the black layer as a band enveloping the whorl immediately in front of the 
aperture. A few non-adult specimens are described ; and it is interesting to 
note that the British Museum specialist definitely accepts the approximation of 
the last two septa as a criterion of maturity. 
A Fatsk Fossm. J. 8. Dituer. ‘Origin of Palaetrochis,” Amer. Journ. 
Seience, vii. 1899, pp. 337-342. In 1856 Professor Ebenezer Emmons described 
two species of Paleotrochis from the so-called Taconie rocks of Montgomery 
County, in North Carolina, and regarded them as siliceous corals, and as the 
oldest representatives of animal life upon the globe. But Hall, Marsh, J. A. 
Holmes, and others denied their organic nature, whilst C. H. White almost as 
strongly advocated it. Mr. Diller determines the Palaetrochis rock as an acid 
voleanic full of spherulites, and concludes ‘‘that Paleotrochis, where most 
perfectly developed and composed of granular quartz, is the result of deposition 
after the spherulitic growths about it and within it had developed, but whether 
this deposition followed soon after that of the spherulites in the course of solidi- 
fication, or took place in hollow spherulites (lithophysae), or resulted perhaps 
long subsequently at the time of rock alterations, is not so clear.” But this 
seems clear that the Paleotrochis is no reputable coral. 
DiptosponpyLy. W.G. RipEwoop. ‘Some observations on the caudal 
diplospondyly of sharks,” Jowrn. Linn. Soc. (Zool.) xxvii. 1899, pp. 46-59. 
It is a well-known fact that in Selachian fishes the vertebrae of the tail are twice 
as numerous as the caudal segments as marked by the spinal nerves and the 
intermuscular septa. Dr. Ridewood reviews the facts and comes to the conclu- 
sion, ‘‘that the condition of diplospondyly in the tail of sharks is secondary, but 
of ancient date; and, further, that it is purely adaptive, being calculated to 
maintain a due proportion between length of centrum and width of body, with- 
out diminishing the length of the muscle-segments. In the region of the body 
from the cloaca to the caudal fin, the demand for increased flexibility is pre- 
potent over the normal tendency of the chondrified chordal sheath to segment 
in such a way that the centra are as numerous as the myotomes.” 
TERATOLOGIA. BreRTRAM C. A. WINDLE. ‘Ninth report on recent terato- 
logical literature,” Journ. Anat. Physiol. xxxi. pp. 507-526. In this valuable 
record, for the continuation of which all biologists should be grateful, Prof. 
Windle gives a clear and terse summary of recent progress. He gives references 
to 83 papers, and arranges the results under the headings :—experimental, 
general, duplicity, head and neck, thorax, abdomen, genitalia, and extremities. 
