BALANUS. 21 



o. Balanus porcatus. Tab. I, fig. 5« — 5g. 



Balanus porcatus. Emanuel da Costa. Hist. Nat. Test. Brit., p. 249, (1778). 

 Lepas balanus. Linn. Syst. Naturae, (1/67). 



— Born. Testacea Mus. Cses. Desc., Tab. 1, fig. 4, (1780). 



— Chemnitz. Syst. Conch., 8 Band., Tab. 97, fig. 820, (1785). 

 Balanus arctica patelliformis. Ellis. Philosoph. Transact., vol. 50, Tab. 31, 



fig. 18, (1758). 



— sulcatus. Bruguiere. Encyclop. method., Tab. 161, fig. 1, (1789). 

 Lepas costata and Balanus. Donovan. British Shells, 1802-1804, Tab. 30, fig. 1, 2. 

 Lepas Scotica. W. Wood. General Conchology, PI. 6, fig. 3, sed non Lepas balanus, 



PI. 7, fig. 3, (1815). 

 Balanus angulosus. Lamarck (1818), in Chenu, Illust. Conch., Tab. 11, fig. 11. 



— TESSELATue. Sowerby (!) Mineral Conchology, Tab. 84, (1818). 



— Scoticus. Brown. Illust. Conch. Great Britain, PI. 7, fig. 2, sed non 



PI. 6, fig. 9 et 10 (1827) : 2d edit., PI. 53, fig. 1-3, 22, 23 et 

 PI. 54, fig. 1-3. 



— geniculatus. Conrad. Journal Acad. -Philadelphia, vol. vi, part 2, p. 265 



(1830), Tab. 11, fig. 16. 



— — Aug. Goula ?(!) Report on the Invertebrata of Massachussetts, 



fig. 9 (1841). 



B. parietibus, sed non basi, ports perf oralis ; testa alba, plerumque longitudinaliter 

 acute costatd ; radiorummarginibus superioribus pcene basi parallelis : scuto longitudinaliter 

 striato ; tergi apice producto, purpureo. 



Parietes, but not the basis, permeated by pores ; shell white, generally sharply ribbed 

 longitudinally ; radii with their summits almost parallel to the basis. Scutum longitudi- 

 nally striated ; tergum with the apex produced and purple. 



Fossil in the Glacial deposits of Scotland (Isle of Bute), of Uddevalla, and (Beaufort) Canada. In the 

 Mammaliferous Crag (Bramerton, Thorpe) and Red Crag (Sutton); Mus. Lyell, J.deC. Sowerby, S. Wood, 

 Bowerbank, &c. 



Recent, England, Ireland, Scotland, Shetland Islands, Iceland, Davis's Straits, 66° 30' N. ; Lancaster 

 Sound, 74° 48' N- Maine and Massachusetts, United States. China (?) In deep water, commonly 

 adherent on shells, Crustacea, and rocks. 



This species can be at once distinguished from all the foregoing by the basis being 

 solid or not perforated by pores ; and from all the following species, with the exception of 

 B. crenatus, by the parietes having large square pores or tubes. From B. crenatus, this 

 species can be distinguished by its longitudinally striated scuta, purple-beaked terga, and 

 by the peculiar structure, immediately to be described, of its parietal pores ; and in most 

 cases even by its general aspect, larger size, and ribbed walls. When, however, 

 B. porcatus and crenatus have grown together on the same irregular surface, for instance, 

 on a Pecten, they sometimes resemble each other in a very deceptive manner. The 

 opercular valves have not certainly been found fossil, but I have given drawings from recent 

 specimens. 



