— 414 - 



dense pilosa tectae; denticulis cardinalibus anticis 7—10, posti- 

 cis 10-14. — Long. 16 Mm. Sars. 



Arca e:lacialis Giay App. Voy Parry >^iippl. p 244 — Torell Spitz- 



bergeii p. 153 T. 2, F. 7. - Sars Norv. p. 43 T. 4, F 1. — Jeff- 



reys Fr. Z. S. 1879 p 572. - Veriill Trans. Coiuiect. V p. 576. — 



Leche Spitzb. p. 29 T. 1, F. 8. 



Hab. mare arcticum. 



10. Arca pectunculoides Scacchi. T. minuta, mo- 

 dice convexa, oblique rotundata, ])arum longior quam altior, 

 antice angustior, postice parum expansa, margine libero arcum 

 aequum formante, cardinali recto utrinque angulato, umbonibns 

 pauUo ante medium sitis, parvis sed prominulis, area ligamen- 

 tali angusta; valvulae subtenues, paulo inaequales, lineis tenui- 

 bus elevatis radiantibus et concentricis subtiliter decussatae, 

 epidermide tenui cinereo-fulvescente pilis brevissimis per lineas 

 radiantes dispositis ornata, denticulis cardinalibus anticis 3—4, 

 posticis 4—5 valde obliquis fere longitudinalibus. — Long. 5 Mm. 

 Var. septentrionalis, duplo major, umbonibus in ^^ anteriore 

 sitis, dentibus cardinalibus anticis 5—6, posticis7— 8. — Long. 

 11 Mm. Sars. 



Arca pectunculoides Scacchi Notizie p. 25 T. 1, F. 12. — Loven 

 Index p. 34. — Jeffreys Br. Conch. II p. 271 T. 30, F. 3. — 

 Pr. Z. S. 1879 p. 572. - Sars Norv. p. 43 T. 4, F. 2. — Weiu- 

 kauff Mittelm. p. 201. - Dall Rep. Blake p. 240 T. 8, F. 5 (var. 

 orbiculata). — Verrill Trans. Connect. V p. 573. - Leche Novaja 

 Semlj. p. 30. 

 Arca raridentata Thompson Ann. Nat. Hist. XVIII p. 385. — Forbes 

 et Hanley II p. 241 T. 45, F. 8. - Sow. Hl. Ind. T. 8, F. 11. 

 Hab. oceanum atlanticum borealem, mare mediterraneum 

 et sinum caribaeum. 



11. Arca pteroessa Smith. C. parva, tenuis, valde 

 inaequilateralis , transversa, subcompressa, antice angustata, 

 acuminata, postice dilatata, oblique truncata, sordide albida, 

 epidermide iibrosa laciniata pallide fusca amicta; valvae aequa- 

 les, in medio impressione haud profunda ab umbonibus radiante 

 constrictae, liris radiantibus tenuibus aliisque concentricis fiexuosis 

 concinne cancellatae; umbones parvi, acuti, haud approximati. 

 circiter in ^/3 long, positi; area ligamenti angusta elongata 

 adamantiformis , postice angustata; margo ventris obliquus, 

 antice ascendens, prope medium leviter sinuatus ; facies interna 

 alba; linea cardinis gracilis, dentibus circa 18 munita. — L. 11, 

 diam. 4 Mm. 



Arca (Barbatia) pteroessa Smith Challenger p. 262 T. 17, F. 4. 

 Hab. in abyssis Oceani atlantici et pacifici, 

 ?Arca Weinkauffi Crosse. T. rhomboidea, Arc, diluvii 

 similis, sed area multo latiore et umbonibus multo magis distan- 

 tibus, crassitudine longitudinem et latitudinem superante. — 

 Long. et lat. 25; crass, 30 Mm. Weinkauflf. 



