62 ON THE APPENDICES GENITALES (CLAvSPERS) IN THE SELACHIANS. 



runs out in an elegantl}' shaped, longitudinally somewhat twisted blade with a peculiar sharp lateral 

 edge. Ventrally of this, and attached to the same edge of the ventral marginal cartilage, is found a 

 piece da'^) which I do not find in the Skate, or in any of the other Plagiostomes I have examined, 

 but, according to Petri and Moreau, it evidently appears in several other /^rt/'ff-species ; it has a 

 thick, lateral edge, and a rounded contour; it is movable and seems to be composed of two pieces, a 

 little, proximal, lamellar da\ and the larger distal da. Finally is foimd the large piece T^/). It con- 

 sists of a more narrow foremost part, the proximal end of which is attached to the lateral edge of the 

 ventral marginal cartilage, and which laterally sends forth a sharp, winglike ridge (corresponding to 

 that in the Skate, but much lower), and next of a broader, hindmost part whose medial edge (corre- 

 sponding to the axe-blade in the Skate) folds round the appendix-styles). 



The muscular system, with regard to the proximal part, shows the t3'pical relations, as 

 will be sufficiently clear from the figures 67 and 68 on pi. VI. 



The Af. dilatator is on the dorsal side behind split into two parts, but this clea\ing has not 

 been carried through to the proximal part of the muscle, and so the J/ dilatator seems. to me to 

 form one muscular mass here as well as in most of the other Plagiostomes I have examined. The 

 whole of the large dorsal part of this muscle is with its hinder end attached to the dorsal covering 

 piece, i. e. not to the edge of this piece, but some wa}- in on its surface till a plainly indicated line 

 of insertion (see fig. 49 on pi. IV). In Raja hatis the division of the AI. dilatator indicated in R. clavata 

 seems to be more strongh- pronounced, and in other /^ff/c?-species ■*) it even seems to lead to a separa- 

 tion into two independent muscles, one larger situated dorsally, and another smaller, ventral, which 



■) Petri: da < ein spatelformiger Kiiorpelstuck > (p. 313); Moreau, who has correct!}' seen that it is composed of two 

 pieces, calls the little proximal one: Cartilage intermediaire, no. 4, the larger one: Cart, accessoire, no. 3. 



2) Petri: hk < hakenformiger Knorpel ; Moreau: (Duvernoy) Cartilage en soc de charrue, no. 7 (in the principal 

 figure, however, indicated by i). 



3) Vogt & Pappenheim's appellations have to be with difficulty- found out from the description, this, as men- 

 tioned, having no references at all to the figures, and in these no letters are found. I give below the appellations of these 

 authors corresponding to my names. It seems that they have not clearly seen that the chief piece — la piece principale — 

 is composed of three parts; thej' use the names <:la levre interne* partly of the marginal cartilages, but without establishing 

 the independence of these pieces; the prolongation of the dorsal marginal cartilage is described (p. 114) as <:une feuille mince 

 en forme de spatule . The other names are: 



The covering piece d = piece externe, la plus superficielle (p. 115). 



Td = piece externe; seconde piece. 



Td = piece alongee, courbee en S ; it is interpreted as coalesced of two pieces , the terminal part wrapping the appendix- 

 stem being called < une petite piece cartilagineuse formant une gouttiere> etc. (this part in young animals is 

 possibly soft). 



da =. petite piece cartilagineuse .... presque carree et couverte .... par un coussin gelatineux. 



Tvz ^= piece .... plus allongee, sa forme est semblable a celle d'uiie equerre tres large. 



Tv =^ une derniere piece cylindrique etc. (p. 116). 



4) For inst. in /?. Schttlisii , according to Petri (I.e. p. 314; pi. XVII, fig. 2 B and C). Petri calls the greater, 

 medio-dorsal part M. levaior, and thinks this part to be composed of two kinds of muscles, \-iz. the greater part of < red» 

 fibres in which is found a wedge-shaped (whites part (fig. 2 B, al) the fibres of which, however, are said to run — onl}- 

 with altered colour — into the red mass (a difference of this nature I never saw in any Plagiostome) ; the smaller, dorsal 

 muscle is called M. rotator with regard to its action on the «hakenfomiige Knorpel > (my piece T^). In Raja clavata Vogt 

 & Pappenheim (1. c. p. 116), as it would seem, (the description is not quite clear to nie) have also found two nmscles where 

 I onh- find one; they speak of a < Muscle ecarteur dorsal-, 'originating* on the large dorsal covering piece (where the fibres 

 of tlieir V M. relevevir* are said to be attached; according to their description this .releveurs for one tiling is composed of 

 the dorsal layer coming from the body (i.e. the tail), and is rather incomprehensible to me); and next of a muscle ecarteur 

 ventral* which by means of <rather long tendons* is attached to the outer side of the <s-shaped pieces [T-^. Duvernoy 

 also says (1. c. p. 308) that his <Muscle grand abducteur» {M. dilatator) in ida raie ronce* is divided in a similar manner, and 

 attached in the same way. 



