1041 



MYTILID/K. 



MYXINE. 



1042 



Pinna t'labtlluui, ful'.-grovrn, valves closed, outside view, with byssus, one- 

 llfth natural size. 



oolite 

 FiUon 



in his list of organic remains of the Yorkshire coast. Dr. 



i, iti his 'Systematic and Stratigraphical List of Fossils' (strata 



below the chalk), enumerates the following species : M. edentulus, 

 M. irutquivalvit, M. lanceolatia, M. Lyellii, M. prcelongws, M. tridens, 

 and an undetermined species. Woodward gives 80 fossil species, 

 principally from the Permian beds. 



Dreiuma. Fossil in the modern Calcaire of Aratapak and Transyl- 

 vania, in Moravia, and the environs of Vienna. (Vanbeneden.) About 

 10 fossil species have been described. 



Here we may perhaps place Mylilva Brardi. The septum comes 

 very near to that of Dreitiena. 



s Tiittrdi. 

 a, Hinge and septum, enlarged ; I, outside of valve j e, inside. 



' Modiola. Mr. G. B. Sowerby states that the fossil species are not 

 many. M. Deshayes, in his ' Tables.' makes the number of fossil 

 species (tertiary) 21 ; and M. larbata, M. discrepant, and M. lithophaga 

 (Ijithodomut), both living and fossil (tertiary). In the last edition of 

 Lamarck the number given is 20. Woodward gives 130 as the 

 number of fossil species now known. They are found from the 

 Silurian ystem upwards. 



Lithndomva. M. Deshayes does not mention this genus in his 

 'Tables,' and appears to place it under Modiola, a position which it 

 occupies in Lamarck's work. M. Desliayes records Modiola lithophaga 

 (Tar.) Lilhodamui lilhophagui as fossil at Paris. Mr. Lonsdale 



BAT. HIST. DIV. VOL. III. 



notices a Lithodomus in the inferior Oolite, and another in the Coral 

 Rag. Dr. Fitton records a new species and another species, both 

 nameless, in the Portland Stone. 



Pinna, The number of fossil species is about 50. They are 

 chiefly from the Devonian Beds, and found in Europe, America, and 

 Southern India. 



MYTILUS. [MTTILID*.] 



MYXI'NE, a genus of Cartilaginous Fishes, of the order Cydostomi. 

 It is synonymous with the Gastrobranchus of P.loch. The Myxinc 

 glutinosa, or Glutinous Hag, is the type. This curious animal is 

 shaped like an eel, and measures when full grown about one foot and 

 a half. The head is scarcely distinguishable from the body, and is 

 obliquely truncated in front, terminating in a large round mouth, the 

 frame-work of which is a membranous maxillary ring, furnished above 

 with a single tooth. The tongue is furnished on each end with two 

 rows of strong teeth. Eight filaments surround the mouth. In the 

 middle of its superior margin there is a single round spiracle. It has 

 no eyes. The branchial openings are two, and are estimated at about 

 one-fourth the length of the body, below the mesial line. The skin is 

 naked, and very slimy. Along each side of the belly there is a row 

 of pores, which furnish the mucous secretion. An obscure fin runs 

 along the hinder portion of the back, is continued round the com- 

 pressed tail, and beneath the anal opening, which is placed near the 

 tail. It is of a dark bluish-brown colour above and whitish beneath. 

 The M. glutinosa is not uncommon in the Scandinavian seas, and is 

 frequently taken off the north-east coast of Britain. It enters the 

 mouths of fishes caught in the lines of the fishermen, and eats up all 

 the fleshy parts of their bodies, leaving only the skin and bones. It ia 

 sometimes called the Hag, and also Borer, because it is said by some 

 that the Myxine pierces a small aperture in the skin, and thus makes 

 its way into the body of the cod or other fishes which it attacks. 



The very anomalous characters of this fish have at different times 

 caused naturalists to place it in more classes than one. Thus Linnaeus 

 classed it among Verities ; Modeer, among Amphibia ; and 0. F. M tiller 

 among Mollusca. That it is a true fish, though very low down in the 

 series, has now been placed beyond doubt. It has furnished the 

 subject of many elaborate essays. The most valuable is the celebrated 

 memoir on the ' Anatomy of Myxinoidece,' by Professor John Muller, 

 published in the Transactions of the Berlin Academy for 1834, illus- 

 trated by admirable anatomical drawings. 



In that memoir the author proposes the following arrangement of 

 the Cartilaginous Fishes, in which the exact position of Myxine and 

 its allies in the series is well shown. 



Chondroplerygia. 

 Skeleton cartilaginous, cranium without sutures. 



Order 1. Branchiostega. 



Family 1. Calaphracta. Cartilage of the cranium and skin of the 

 trunk covered at intervals with cartilaginous tubercles. 

 Sturiones. Genus 1. Sturio. 

 Family 2. ffuda. Body without tubercles. 

 Spatularice. Genus 2. Spatularia. 



Order 2. Jlolocephala. 

 Genus 1. Chimara. 

 Genus 2. Callorhyncus. 



Order 3. Plagiostomata. 



Family 1. Sqali. The branchial apertures not attached to the head. 

 Genus 1. Syualua. 



Sub-Genera. 

 Muitelus. 

 Scymnus. 

 Notidanus. 

 Selache. 



Ceslracion. 



Spinax. 



Centnna. 



Scyllium. 



Carcharias. 



Lamna. 



Galena. 

 Genus 2. Zygoma,. 

 Genus 3. Squatina. 

 Genus 4. Pristii. 



Family 2. Kaia. The branchial apertures attached to the head. 

 Genus 1. Rhinobalut. 

 Genus 2. Torpedo. 



Genus 3. Raia. (Sub-Genera Raia, Trygon, and Anacaretlnis.) 

 Genus 4. Proptei-ygia. 



Genus 5. MylMates. (Sub-Genera MylMatet and Rltinoptera.) 

 Genus 6. Cephaloptera. 



Order 4. Cyclostomata. 

 Family 1. Ifyperoartia, palate imperf orate. 

 Genus 1. Petromyson. 

 Genus 2. Ammocretii. 



Family 2. Hyperolreta, with the palate perforate. Myxinoidea. 

 Genus 1. Myxine. 



Miiller enumerates only one species, the M. glutinosa of the 



3 x 



