23° 



HARDWICKE'S SCIENCE-GOSSIP. 



the world. Among other regions, they have been 

 discovered in Belgium, France, Spain, Italy, Malta, 

 Arabia, the West Indies, South Carolina, Central 

 America, and New Zealand, and derived specimens 

 occur in the British Crags. It is interesting to note, 

 too, that numerous examples of equal size, and 

 probably the same species, were dredged from the 

 bed of the Pacific Ocean by the " Challenger " expedi- 

 tion, — a fact indicating the comparatively recent 

 •extinction of the huge sharks whose dentition they 

 constituted. C. sulcidcns is a smaller species, with 

 the teeth mucli flattened, wrinkled longitudinally at 

 the base, and destitute of lateral denticles, occurring 

 in the Pliocene Crags of England and the Lower 

 Tertiaries of South Carolina. 



Two other genera, Sphenodus and Meristodon, 

 from European Jurassic strata, are regarded by 

 Agassiz as the forerunners of the Lamnidre, but are 

 very imperfectly known, having been founded merely 

 upon the crowns of broken teeth. 



XOTIDANIDyE. 



Teeth of Notidamis, the single living genus of this 

 family, are met with in strata so early as the Jurassic, 

 and occur in most of the marine formations of later 

 date. N. Mihtsteri is Jurassic ; N. microdoii and 

 N'. pcctinatus, Cretaceous ; N. serratissimus. Eocene ; 

 and N. primigenms, Eocene, Miocene, and Pliocene. 

 The first of these species has not been recorded from 

 any British formation, but the four latter are known 

 from several localities, and are not unfrequently met 

 with. It is singular, however, that the teeth of the 

 upper jaw, which differ much from those of the lower 

 in the living species, have very rarely been recognised : 

 fig- 139 represents one of these uncommon specimens 

 from the Middle Eocene of Hampshire. The ordinary 

 fossil — the mandibular tooth — may be described as 

 •consisting of a series of sharp, compressed cones, 

 more or less oblique, and placed one behind the other 

 upon a well-developed root, the foremost being the 

 largest, and the rest diminishing in size as they 

 approach the hinder end. Figs. 140, 142, 143, are 

 sketches of the three most important British species, 

 and indicate their characters better than any descrip- 

 tion : it will be observed that, in each case, the 

 length of the crown of the tooth is much greater than 

 the height, — the ratio b^ing frequently more than 2 : i. 



SCYLLIID.^. 



Clusters of minute pointed teeth, in association 

 with more or less fragmentary pieces of calcified 

 cartilage, are sometimes found in the English Chalk, 

 and most of these are distinctly referable to Selachians 

 of the family of " Dog-fishes." In the table at the 

 •end of our last article (p. 174) we alluded to the fact, 

 that in the Scylliidae several rows of teeth are 

 generally in function at the same time, and an exami- 

 nation of some of the more perfect specimens of the 



chalk fossils, just referred to, can leave no doubt but 

 that such was the case in the ancient fishes of which 

 these are the dilapidated relics. The fossil teeth are 

 frequently not much more than -/^ inch in length, and 

 consist of a central sharp-pointed cone, with a 

 slightly diverging denticle on each side. Agassiz, 

 who had excellent examples for his study in the 

 cabinets of the Earl of Enniskillen and Sir Philip 

 Egerton, founded upon them the genus Scylliodtts, 

 and described a single species, S. antiquiis. These 

 type-specimens, now in the British M*useum, are 

 sufficiently perfect to reveal other characteristics of 

 the shark besides the dentition, and exhibit remark- 

 al)ly well a portion of the vertebral column. No 

 other dog-fishes have been described from British 

 strata, but one species of the living genus, Scyllium, 

 is known to occur in the Cretaceous rocks of the 

 Lebanon. 



• ON OUR BRITISH SEA-WORMS, 

 By Dr. P. Q. Keegan. 



OCCASIONALLY, when exploring the fauna of 

 the extreme limits of the tide-abandoned shore, 

 we turn up a stone whereon we perceive a very long, 

 slim worm of a peculiar purplish colour fringed with 

 brown, and furnished with a lavish amount of feet 

 that move in a regular, waving, rythmical manner 

 adown the flanks. This is Phyllodoce' lamelligera, a 

 very beautiful form enrolled in a genus characterised 

 by the deep and well-marked separation of the body 

 segments, and by the series of beautiful broad leaf- 

 like ciliated branchise on the sides for the aeration of 

 the peritoneal fluid (the blood-proper being scanty) ; 

 the proboscis is beset with glandular structures filled 

 with oleous cells and globules ; the blood is colour- 

 less, but the bile is dark green. P. lamelUgera is 

 sometimes two feet long ; the head is roundish, with 

 a number of rather conspicuous tentacles on or near 

 it ; the branchiLV are of two sizes, one half the dimen- 

 sions of the other, arranged alternately along the 

 sides, and penetrated with an exquisite network of 

 blood-vessels. The bristles project between these 

 lamina:, and are slender with a dovetail, elastic, 

 flexible ioint, and a single yellow spine in the middle 

 of each brush. P, viridis is a smaller species, and is 

 immediately recognised by the bright emerald green 

 colour which seems Xo deeply tincture its entire 

 structure ; there are five antennre ; the branchiae are 

 lanceolate, being narrower and longer than in the 

 last species ; the bristles are jointed, and very slender 

 and sharp at the point. 



When trowelling about the loose, damp, clean 

 sand near low water, you are pretty sure to disentomb 

 a lithe and supple worm tapered at the end, and of 

 a bright silvery iridescent hue. This is a species of 

 rag-worm (Nephtbys), a member of a genus which 



