Fa . 5 Dy, a BY ry 4 - f > > a 5. r ‘= x = a . 4 e i= a z ———— of % > ' mie. |S KINCRED Lacy. == —-—. me THE SKULL OF AMIURUS. & j ! ] h > bad \ ) h 45 Digitized by the Internet Archive in 2013 http://archive.org/details/skullofamiurusOOkind THE SKULL OF AMIURUS BY JAMES ERNEST KINDRED A. B. Tufts College, 1914 A. M. University of Illinois, 1915 THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY IN ZOOLOGY THE GRADUATE SCHOOL OF THE UNIVERSITY OF ILLINOIS 1918. a“ ‘ , = Oe . 4 - eh ,. re i a 7 es" ‘S ’ . af 7 apt tp ose Teg" Ba * <3 "4 = ’ 7 Le ‘ he ard a) - 2unuIMa 41. tae! UNIVERSITY OF ILLINOIS THE GRADUATE SCHOOL Frag b pene | HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER MY SUPERVISION BY James Ernest Yindred ENTITLED... the Sknil of Amfiurus BE ACCEPTED AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE DEGREE OF_Roctor of Philosophy in Zoology 7 In Charge of Thesis Recommendation concurred in* Committee Se on Final Examination* *Required for doctor’s degree but not for master’s A INOO far y i > AIKAIQD JO0HDe aTAUGARO, 3 iT _ Te HT TART G4EMMOONHA ORT, eas Ya my } ) , , ' nO+ : tit : ; .) nA aH ol Lt kar 2a : y at f > A H a 2 AY, 7 = : ‘ : a ee | ' « “tl bestmnoges" cs ¥ ' Panes | S * te peer ati _, 5 = _ a , Worl KS7 Contents. page UMM CMON | i'n ceca a: wi alu a Miaiaiuialal ging ataldia: @e-4.a @)a <0 Om or ae des Ais O:aue & «5 6:4 yak Wee ew balay aig Oe MS as 6 odode were ee Serer At he oe. Lad iol Cocsuepe legen ae F eek heh adh Fp oesaces eens MSR DO OOREL © A OT Pre Pre Pore ts es cocscenscl Pig ons iems S'S rr rrr erie ee joke tdacdta weer a é Rater ra Pista ous be cea de oad as wr ree rr eccec a ORS a tliat Cheeta a verre SE Sead Gio 2.6 a err Tee ton cad oa - htogytedqot off eeeeeseeaeeeseuunene ©@ ¢0 «a6 0 '6)414 5 4618 Sioa aaa based oie & @ ae sane ddiont& Gale o's aed ee sence te eta, cud oa 05 Ve baeenen ... th LeCt icamows i seh 4.6 44.0 abel er eer Ty © VEereerrrrecy., ey rT ere re errr ae & teseces ne ees RA CRT TR Haale eb ht wy ba & hae be coe eeeeeeeeeeeee SOLU OTOE Oy ae a ek Sek i er scrcenesscsecseensss +s sO LRROOREEE TOF rey, + Cts temeacdcne se OD EEE oteqo i a eC oor iz Rug COP SOHO MO HOMER ERA EK DEE EO Od OD 649 0)9 0 re Stee teste seen sa cee nen setlig ees es SOMREL ae yom tt a6 POP CLEC Ce FOO eT ere ae ne ee en ee eee ee DP Ee Pt a Vigra ~ - SMERAERREEEEROV ENE OT EY ft SREBRE SS! 2. , - e¥ = * = | Introduction. The study of the development of the teleost: skull has been confined for the most part to isolated stages and there have | been very few papers dealing with the changes which take place in any one species. Parker's ('72) work on the development of the cranium of Salmo has remained the standard and hes been sup- plemented by Gaupp ('02) and Schleip ('03). Winslow ('97) des- eribes the chondrocranium of the trout, Ryder ('86) and Pollard ('95) the chondrocrania of some of the Siluroids, but none of these attempted to trace the formation of the bones and their relation to the cartilage, in the same way that Parker did. Swinnerton ('02) has described several stages in the development of the skull of Gasterosteus. The skull of the adult teleost has been widely studied in a topographical way, but very few authors have analyzed the bones in terms of their developmental relations, so that a wide field is open for this line of investigation. Gouan (1770) gives a Simple account of the bones of the cranium and naively states that although there are many bones in the cranium of the young fish, these fuse into several large bones in the adult,as in man. Many of the names in use in the terminology of the present time have come directly from Cuvier, but others have been introduced into the literature principally by Owen ('48), Huxley ('64), and Parker ('72). Except for a few scattered references to the cran- ja of Silurus glanis, Clarias, Auchenaspis, and the incomplete description of the cranium of the adult Amiurus by Melurrich ('84) Fs ’ * ~ fat ok? to tnemgoleved. eft 16 see Y : t ‘ ' i 1 crop uret! ' : . ; oe : mf. i od? eveda 5 ae ‘ebte Te 4 ats ot yiao ou han \t merd be = a9 : y ) ‘A ot ol? of 10" . nem oe C _— of the glossopharyngeal (fig.1, 1#) and vagus nerves (X), nothing comparable to the posterior basicranial fenestra and the basicapsular fenestrae of Salmo (Parker, '72;Gaupp,'06) being Ohserved. The cavum of the labyrinth opens widely into the cavum cranii. The alisphenoid cartilage, extending dorsally and anter- iorly from the anterior end of the otic capsule, forms the dorsal margin of a large foramen in the cranial wall, through which the optic,oculomotor,abducens, trigeminal and facialis nerves issue (figs. 1,2). The nerves penetrate the connective tissue membrane which extends across the fenestra from the alisphenoid cartilage to the trabecula cranii (fig. 14). The detailed descriptions of the various regions of the cranium and the comparisons with the chondrécranial parts of other forms follows below. The ethmoid region. At the 10 mm stage in the development of the ethmoid region, the dorsal surface of the cartilage forms a trough, the sides of which are formed by dorsal projections near | the lateral edges of the plate: the floor is formed by the ethmoid plate itself (fig. 2). The olfactory lobes lie in this trough and are roofed by membrane which extends between the two lateral projections and is attached dorsally to the epidermis. The olfactory foramen, which is very large at this stage, occupies the anterior half of the lateral wall of this region and the olffactory lobe protrudes through this foramen (fig. 1). A short olfactory tract extends from the lateral part of the lobe to the olfactory bulbus which lies just lateral to it. The ethmoid plate extends laterally beyond these walls (fig. 30) and forms the floor, called by Gaupp ('06) the solum nasi in Salmo, of the nasal fossa of each side (fig. 2). The anterior end of the add en Pris ' asnet | * i vip sip os “ ss oY. a 2 4] 4 r t } tz y pe : : ) i 7 kaa i é' {[ dotdw exdind v0 ps > ede 5 plate projects as two massive cartilaginous processes, the ethmoid | cornua (fig. 2). dust behind these a transverse ridge in the mid- | dle of the plate forms the anterior end of the cavum cranii and marks the anterior extent of the olfactory lobes. The ventral surface of the ethmoid plate is slightly concave (fig. 30). At the posterior end of the ethmoid region, the anterior ends of the fused trabeculae and alisphenoid cartilages fuse with the side walls and floor of the trough and the floor forms the anterior margin of the fenestra hypophyseos (fig. 2). Each lateral wall of the ethmoid region is produced laterally into an ectethmoid process which projects abruptly from the external face of the cranial wall and the ventral face of which forms the articular surface for the palatine cartilage (fig. 1). The amterior face of the process is concave near its ventral margin: the ophthalmic superficialis ramus of the trigeminus passes obliquely through the dorsal margin.| The posterior face of the process is fused medially to the anterior} dorsal margin of the alisphenoid cartilage. The ventral part of this fused region is separated from the trabecula by a small foramen,behind the ectethmoid process the orbital foramen (fig. 1).| This foramen is the posterior limit of the ethmoid region or wall. As yet there is no internasal septum between the olfactory lobes of the two sides. The oblique eye muscles have no relation to the ventral surface of the ethmoid plate as thay have in Salmo (§aupp '06), but are attached to the ventral margin of the orbital fora- men posterior to the ectethmoid process. Sagemehl ('85) discussed the morphology and development of the olfactory region in the different families of teleosts. He recognized three different degrees of relationship between the ute ) egoie eereveresd 6 88 7 its . batt fied Japs «13 « 7 ’ o> if > 5 ¥ an wh 7 Dad we uirve: tf? to Sue tto2-r6da8 entd emret wwe om”. isriney. ents : S “ort oaltc | Se tiedze con xétme 4 att “a ZA .108 ws “yeonkoo WEthial ' efsic Blomlte add Pet . ~ - , * ait) nite eft to bxe ToPtebee , “<. $3 en ities btoasticetie tina eslvoedaat”™ cid stost) ae SOosBr Ientae v % ot: call ee ot tes e ’ . i S¢ , a Rirred rc one et oF Bde: _ ie | bition’ oa 5 ont wie os ci nih a. bi fant: : dt Ye @ost we ro ike : , at motget ‘ Store: ‘ tos 7 TOT 80 ut . » in 6 olfactory organ, the bulbus olfactorius, and the brain. In the first and most primitive relation which he described as the Cyclo-| stome type, the bulbus lies between the brain and the organ within the cavum cranii, closely fused to each. With subsequent develop- ment a long tractus olfactorius is spun out between them, and the bulbus remains applied to the olfactory organ. He called this the Selachian type, as it is most common in this group. It is also found in the Cyprinoids,Siluroids,Mormyrids, and Gadids among the teleosts. In these families the tractus always lies within a canal directly continuous with the cavum cranii. In the other teleosts families, as represented by Salmo, @ membranous interorbital septum is developed between the orbits, on the dorsal surface of the trabecula communis. This septum, by growth backward and dorsally, limits the anterior extent of the cavum cranii. The bulbus olfactorius, which in the larva of one of these forms, has the primitive cyclostome relation, is carried posteriorly by the interorbital septum, so that it becomes enclosed within the cavum cranii. The bulbus retains its connexion with th¢ olfactory organ by a long slender olfactory nerve which passes unenclosed across the orbit between the anterior end of the cavum wall and the ectethmoid process. Sagemehl recognizes this condi- tion as the teleosts type of olfactory development. It is also interesting to note that in the Characinidae (Sagemehl,'85), Citharinus is very close to the Selachian type and Macrodon has the teleostean relation of parts. Other members of this family presen} greater or lesser degrees of relationship to the two types. The olfactory region at this stage of development in Amiurus, according to this view has just reached the cyclostome stage. : > . y q 2 ’ —~ * an - ot aa’ 3 ass rid @G: ». Dike Mire Oe | _—-, * " me ove Sra? ss 7 my ~ - ; rs : ee es ‘pi: ee, th ie it as , hod: opeb et nobiv notte at ovivte a — ‘aia edt Bus ntetdé off assented ee kl enti aa a - Ca * : as avi é r a t emvulyo oft +tingto mitveo ott mb Fi fof a ww negro po 1 es | : iid+o elt eeoton beacl om me =i Db; , te Sloat evne ont 5 se if : | fo to eqyut eteceiet ane: an a 7 q ; i tadé etom ot saree aole yrey hav: aust. sa 7 The orbital region. Each lateral wall in the orbital region of the 10 mm Amiurus is formed by a ventral trabecular and a dorsal alisphenoid cartilage, between which, the optic, oculomot or, most of the trigeminal, the abducens and the facialis nerves pass outward (figs. 1,2). In front of the opticus these two cartilages meet and form a solid wall for a short distance, its continuity being broken by the orbital foramen, dorsal to which, the alisphenoid is fused to the posteriorr:face of the ectethmoid process. Posteriorly the alisphenoid cartilage is fused to the anterior face of the otic capsule. Aconnective tissue membranous wall connects the ventral margin of the alisphenoid cartilage with that of the trabecula and it is through this membrane that the above mentioned nerves pass (fig. 30). The ramus oticus of the facialis nerve passes ventro-dors- | ally through the alisphenoid cartilage, just anterior to its union] with the otic capsule. At about the middle of the cartilage are two small foramina, the more ventral for the ramus ophthalmicus superficialis of the trigeminus and the more dorsal for the oph- thalmicus superficialis of the facialis (figs. 1,2). After its exit from the cranium and its passage through the orbit, the Ophthalmic branch of the trigeminus passes through the orbitonasal | foramen of the ectethmoid process, mentioned above, while the ophthalmic branch of the facialis passes around the lateral margin of the process. A cartilage bar, the epiphysial bar, described by Sagemehl in the adult Characinidae and Cyprinidae, and by Pollard ('95) in the Siluridae, extends across the dorsal surface of the fore- brain just posterior to the ectethmoid a g gt f, 4) a ia ete l ege an 28. 4 a . ta s fs noire £ vod Benrot «f & © .fiteo eft ,datdw meertsd ,6 aft ao BE ba asta poe. tigo 4 Lusedet | x». a “— fers ott bee one } 7. b- ordi enany « iigtest edt Yo eagolve estat an ’ a ots iqatl 2 od? yuett etvihan of o edt woh: se eer rO% fie rs ; edt %o ette to! ha | | x | - A ; ° « , 4 %, : fp oltre os 2 rgd ef | ve ‘ , i its tot aero xii ott ye fer tmeaixt eds to okerd ntad i Ay: i i Josecony btondbotee Witt 8 ail it to sncduat aad te 7 : i - : . ; au Td it P : toa tos arf , ted | af itee f | , laltev® base @ab anew cmas - To & oo te Yr tj ebsae3 re aie5 olveds 8 processes and is fused at each end to the anterior dorsal ends of the alisphenoid cartilages. There is no other trace of a cranial roof in this region at this stage. The alisphenoid cartilage was described by Sewertzoff ('97 in the larval Acanthias as a large cartilage lying lateral to the fore- and mid-brains and connected secondarily with the anterior paracordalia. Later it fuses béhimd with the anterior margin of the otic capsule and below with the posterior end of the trabeculae | cranii enclosing the optic, oculomotor, trigeminus anf facialis nerves. It grows anteriorly to the ectethmoid process, and indep- endent cartilage and fuses with it. Dorso-medianly it grows toward the middle line and unites with its fellow of the opposite side to form the solid cranial roof. Except for it ventro-post- erior relations the alisphenoid of Acanthias can be compared to that of Amimrus. In both, these cartilages form the anterior and dorsal margins of the foramina for the nerves, mentioned above, and extend across the dorsal part of the orbit. There is no cartilaginous roof in the chondrocranium of Amiurus with the exception of the epiphysial bar, which may be a remnant of such a condition. The notch at the anterior margin of the optic fene- stra of Acanthias is suggestive of the orbital foramen of Amiurus. Parker ('82) recognized three cartilaginous parts in the lateral wall of the orbital region of the chondrocranium of Acipenser ruthenus. A posterior alisphenoidal part, lateral to the paracordal plate; and anterior orbitosphanoidal part; and a dorsal supraorbital part, which fuses with its fellow of the opposite side to form the cranial roof. The orbitosphenoidal ~ Dak, e: a no Pte fos ens OF DNS ati aS re ~ J 2 'i¢ “eats «sito. on et matt acseeb asw apal Lise. ‘plonedgetto, a i of fetetal nalvi enalftaso syisi 2 Ge eebdvneok Lewaal | 2) .° » : ee oc id rs wrod sse.tosnmntos ors enis iecmia btus > s 10 Ginuias sol iss it d¢lw beddbd csewt If aedad ab Lebaooe sHeadet ge rorta ‘ 4 r 4 PF i : (M00 r (86 ‘Tew oe 2d ) rr a baoa A Leunoddet toed eqte , tag Led tdsonngen, La ‘t ? 1 oa sd laine edit mxo ot. of ebta_ 7 eee Te tea a4 WEA: 10 the Teleosts in Gasterosteous (Swinnerton,'02),the Characinidse (Sagemehl,'85), the Cyprnidae (Sagemehl,'91) and other Sluridae (Pollard, 95 ), is the striking feature of a comparison between these two forms, as Polypterus is specialized in so many other features, that it differs from g@ven the majority of the Ganoids and has been mentioned as representing the ancestral stage of the Stegocephali. In Gymnarchus niloticus ( Assheton!00 ) the early chondrocranium of which has been very briefly described from Budgett's collections and notes, there is a long slit-like fora- men in the wall of theq@bit just anterior to the otic capsule and a smaller anterior foramen separated from this for the passage of the opticus. There is also a transverse bar similar to the epiphysial bar of Amiurus and Polypterus, connected however with the anterior ethmoidal roof by a median longitudinal bar of cartilage, which divides the anterior fontanelle into two parts. this may be the representative of a group in which the reduction from the solid cartilaginous roof of the lower @anoids is taking place, a continuation of which would produces the condition found in Polypterus and Amiurus. In Salmo salar (Parker '73; Gaupp '96) a cartilaginous bar extends on each side of the cranium above the orbit, from the anterior end of the otic capsule to the posterior margin of the tegmen cranii, which extends bck as far as the middle of the orbit. Posteriorly, between this bar and the otic capsule, the branches of the facialis and the jugular vein pass through sep- arate foramina in the cartilage. The bar itself, called by Gaupp the taenia marginalis extends anteriorly above the trigem- a ye et - Se —— joeseeag oat 161 altdt mori basetaqsa fi "202 rehod ere mOqdt ,.3idac ent svods mutnai sft to she toa@ M0 ee ) edt. (20" ea oe Peery vento bre (fe! one neetted aoettaqnos a’ to eait8e2 3 | AANS Nbeel be ot Heb ELetoede’ vt eure a to etttonsd off to ytincten edt on 2 ie ron 8 aa @ > rebel B3 Yo egete [ettesons ott guitasasiqet 42° “— . eae pe r a _ in viwie edt ( 00! notenaca ) evoldol her ste ee moyv? hedistsesh ylisi«d yrdv assed aac codaw 0 om ea701 elti-tile snof s at erent . aston bas svt sigaqad sivo odt of nolteda8 seut Sree eas’ ve emt o3 telimie ted eatsvenatt es coals ef easdT - vst qavewod betoennoo ,suistqylot bag ours, to 48d Wo sad [antiviteool nethex » yd Qoé+ Labtousde “10 fs seditag owt ofa! elleaetsot wtrotin afd ‘gent nen? au golsovie1 sif dotriw nk quot a to ovifatoonbaget ont 6 a gotdat ef eblonegh towol eit to toot anontyetnsiree. i motsinnes ent esoubowy bluow dotdw To paneer , Oty lgty — sucnigaitiqcao 4 (3Q@' qqvad :ST' velvet) aekae piri othe od? ‘to migupa Totietsca sdf o¢ eluaqas otio GBP to ‘Be eit Yo ofBbtit odd se wt oe itod ebosdxe AOde od! ,6ivageo otic ent Bre aad eid? aeswidd censor tte | “dee fgueitd enaq Wlev ashugut of? bie ontaton® efit Ye vo belies ,Llentl aad eT ogeltydes’ ene at ne {Pe “megitt off eveoda rlaiolsedin abnedxe elientyam a ae - oe a le ane ar gt » a A en me thn = — ——- _ a A me > ae A 11 inus and does not enclose any of its branches. Here, as in Amiurus, the large fenestra left in the wall between this carti- lage and the trabeculae cranii is closed by membrane, through which the nerves issuing from the cranium pass. In Amiurus as we have seen, both the fifth and seventh nerves issue through this membrane and with them the external carotid. In Salmo, as in Acanthias these two nerves are separated from each other by a bar of cartilage, thus showing a nearer degree of relationship Selachian than to the Siluroid condition. The closer resemblance of Salmo to Acanthias is again evidenced by the presence of a well-developed tegmen cranii, not found in Amiurus. In Cebatodus and the Urodeles, the alisphenoid cartilage is fused ventrally wihh the trabecula during the first stages of development and later unites with the ethmoid and otic regions. As in the Ganoids and Teleosts, its anterior end and the trabecu- la anclose the optic nerve. Since the posterior ends of these cartilages enclose the trigeminus and the facialis, there is no question as to their homology with the alisphenoid and trabecular cartilages of these groups. Gaupp (06) calls the former, the crista trabeculae, thus adding to the confusion of names. This same author claims that the cartilaginous bar, following the Sewertzoff, called the alisphenoid cartilage is not homologous with the alisphenoid cartilage of the Mammalia and therefore cannot be named such. He says: that=the ala tempor- alis in the mammalian cranium is a new formation homologous with the process basipterygoideus of the Lacertalian cranium, which arises from the procartilage cells around the anterior end of the palatopterygoid cartilage. i Va ’ : a = ; ee an »y 7 is aie ; ‘ ee mines: ) dgwoads \ametimen yd beacfo et Linag® estudsdact edt + tem Vem ee evwima ct .oseq mutharo edt ort gabvest neni eld? dguowlt eseat esvren dénevee bois AdTtt end Atom , | ait és .omfaR al .Sivoxas [cnrtstxe ont ment dole pas ® a 7. as # yd tedde does mort bstavaqer ote BevTer ows oBedt @lienctiafen te se1rgeb ter9esn 2 gatwoiie evit ,opeltiass - | somald@zose: weecio eT .nclifhnoo pron be ad? of qadé tdozls! 7 @ tc songeeao adt ¢¢ bsonebive ciane et cetdinaoa oF a -eteulwA m2 bevel ton ,tiasdo asmged Seqole Sgaittues blomeriqetia ond ,eslsborl sd? dae exbodated a ‘ i Yo wenete tattt odé gndecsb sluoodaw aft rdw ei lersnuew B a semolsey oho base blonite oft dttw vetian tetak Sue sxosdat! eft See boo rolretns sf! ,stsosieT Ona sbtored ond easd? Yo ebits rolroiecg ent esntc .evwren ottao ond ware 18 2 , om el otent .etietost odt bre euninogirt eit sno lone i tafooedat? bee blonedaqella ont tte yaoLomen ated oF ae iy ons .temret edd elfso (20) qqvean . .qinets “epedtt fe esoman Yo Aolbsu'incs sid¢ 6) a0fhbe euc? i sued ~ted svorclisneltital ody jad! amielo conduse omes alaT el epelléio bionerqetia efi belleo ,.ttostreee ori? gatwost 2 ’ aes | "i ai ie A . -toqme’ ele eddeiagt:e¢ec oH .tove bemen od Songed ome) i ant Pie » 4 Aiiw evogolomed aolianto? won 2 el aytasto matlanneat ent Ps all fieldw .autnato aellaedstosead add Te ~wohegee an of % base tolbredoe oft beworw elloo eyniijissorg one nort al? a tty a eee alinmeas ocd to eneltinao bioosdqeiia Sad Mate eyegel ; . -oaalliraas bhogys t2 On comparison with the alisphenoid of mammals this homolo. gy falls to the ground if the relations of nerve and cartilage are used as the criteria for homologies of the chondrocranial parts. Throughout all of the lower Gnathostome groups the poster- ior end of this cartilage is connected with the development of the foramina for the passage of the branches of the trigeminus, but when such a cartilage appears in the mammals, the above associations are discounted and the cartilage is compared to an outside formation. In denying the homology, Gaupp takes this question into cpnsideration, but maintains that theenerve relations are secondary and that nerves go through the ala temporalis be- cause it replaces the original wall of this region. Assuming this to be the case, he states that anybody who relies upon the passage of nerves for their criteria of homology of cartilag- inous parts is sure to err. ('02) It is a settled fact however that nerves are constant throughout the vertebrate series and that they precede the cartilage in both ontogeny and phylogeny. Therefore, any homology which is made with these as a basis is sure to have a landmark which varies less than the parts of any other organie system, suck as the blood vessels or muscles. The trabeculae cranii are flat and acute on both inner and outer edges, becoming narrower anteriorly before uniting with the alisphenoid cartilages. Their posterior ends are fused with the anterior paracordalia and with them form the lateral margins of the fenestra hypophyseosand the fenestra basicranii anterior @¢ figg.2.14). The anterior ends are fused to each other median to their union with the alisphenoid cartilages and form the posterior margin of the ethmoid plate which has been discussed. (Be ene onohtaror * — nee con fatnarworitods edt ‘to asigoLomert whieh Bicoq edt aqtiors omodaodsand vowel edt Tp Lia apenea: os 2 to smbnaoLeveb sift Atiweetooancs st eyelitans ana? | | porimes bt eft Io sedomwead sdd to sgseeeg edt 1O1 asnolmet02 eveda edt ,ofaumam eat nt avesqce egeltiuas 2 dove ew ae oF Detagmoo a! exe(titag orld baa badavocerbh e128. aimed asind qoust .yacfomod od? gatyaeb at Mot Samet0% stgafen svvemcedt Jed? antetaiam tud ,soldatobiango eter. to -ed eliancgms? efe ails dasorudts on seven tad ban 7 oftimuaaA .meipe: alds to {Law Isnigiao edt pe: on goqu eetier cin ~hodyna Jad setate eg «sao edt ed ¢ egelitass to yygclomord Io sziaesis9 ated tot mevisa to savencd toat Soittse a at #3) | (sO) Sct OF ome at edisq bae soles stesdesiey edd SuSiguotwds Saatanoo ets pevisa “Yategofytiq bia ynégotnc:diod at, syeliéiso ent sane, went . et eterd o ne s2edt Mttw ebem at dotaw ygoforcd wa <2 yes to atuet) oft modd cael estaev cdoinw aqeabret g oved one | .rgfousn 16 P£seeev boold ea} ae dove ,wednymotaagio ys 7, aw = baa tomurt diod ag sites bae dal? ote thas ealuoodatd Jeat re) . | edt dilw noliiny evoted ylioldedas Tewoxrrse goimooed,: onesie 0900 ori ftw beest e12 abne tolustecqg she? seepalidaep bhowsiiqatia anin‘rem L[ayodel odd mo. asad? déiew Ors at Labioonang, ager | | solseins lLinetolaad aid esha ent? brs nobaydacagd pa) eenet : ae aalbem Yento cose of beam? ext ebro qotisdnm em? hoes oe off mxcl bose segelliwo blonerigad lip edd aole so bea ebesewoelh aoed aad doldn odalq bigadie ent Ge haul fy; ge There is no trabecula communis such as occurs in Salmo, the cranium being distinctly platybasic. An internal carotid artery approaches the trabecula of its side ventrally, and enters the cranial cavity through the inner edge in about the middle region of the orbit (fig. 2 ), and proceeds‘ anteriorly in the membran- ous wall of the orbit. Each artery sends a branch along the dor- sal surface of the optic nerve and then unites lateral to the cerebral hemispheres with an internal branch from the external carotid. The rectus eye muscles and a ligament to the pterygoid cartilage are attached to the lateral surface of each trabecula in the posterior part of the orbit. fPhere is no trace of a myodome in this or the later stages. The oblique eye muscles are inserted on the trabeculae below the orbital foramen. The fenestra hypophyseos and the fenestra basicranii anterior are closed by a sheet of fibrous connective tissue which stretches between the trabeculae (fig- 14 ) and extends anteriorly below the ethmoid plate @nd posteriorly below the paracordal plate. It is not intimately connected with the cart- ilage of any of these parts. In a 19 mm larva of Amia, the rectus eye muscles are inserted in a ppace between the brain and the trabeculae, in- cluding some connective tissue with them. In the adult Amia in this region there is a canal separated from the cavum cranii by the prootic ossification. The trabeculae are wider in Amia than they are in Amiurus and forms a trabecula communis plate before fusiing with the ethmoid plate. In Amia each internal carotid artery passes through the trabecula on its medial side. ; . ‘elf venifad nt atusove un tous ata ‘pines bijouas Lantesat of ioleady ie oe, nts } edt atedas bane ,.yilarvtneav sbia ott +6 esas ‘ait TW “notssa efbble ent Jyode at eghs terat edd Hgwondd eth P=neidmem afd at elie ttetmiebesso19 brs x S - gt?) dtdxo | 105 ef] gocfs donatd s shyee yareo ts doadt .tidto edd mivvaeo ed? non? bstareqee L[ameo a at e-veds fo k3e7 pe J almA ol 1eble e10 ealusodait af? .nolisot ikea pear sfelq elnummoo alsgoedetd a emi0l bas eiiiail at etn pat factetnt dose ated cl .otalq blemdte ett diie aati ant 3 eeblia Ialbom oti nO sluvedat ed) siguondd eeesaq yIs. % Poss tte . - aa ir a ES The artery gives off a branch above the optic nerve in Amis as it does in Amiurus. The fenestra hynophyseos is even smaller than in| the known higher teleosts, in the former. In the cranial wall anéerior to the otic capsule, the fifth and seventh nerves sre separated by a bar of cartilage between the trabecula and the otic capsule, as in the Selachians and the Salmonidae, differing in this respnect from Amiurus. The oblique eye muscles in a 19 mm Amia are inserted in a foramen in the wall of the cranium between the ectethmoid process and the optic foramen, comparable to the orbital foramen of Amiurus. In Amia this foramen continues anteriorly with a groove on the dorso-lateral surface of the ethmoid plate. Beyond the eye muscle insertion, the olfactory tractus continues along the anterior part of the same groove. In Amiurus this groove is lacking and the eye muscles do not enter the foramen. There is, .however, a concavity on the anterior face of the ectethmoid process which if continued through to the posterior would at the anterior margin of the orbital foramen and may have some significance in comparisons with the anterior continuation of the foramen in Amin. The cartilage of the ethmoid floor in this region between the anterior parts of the orbits, is thiscker in Amin than it is in Amiurus. In the Acanthies larva (Sewertzoff,'97), the trabeculae develop as pairéd independent cartilages at right angles and ven- tral to the anterior ends of the parachordals, eventually becom- ing fused with its ventral face. They grow forward on either side of the hypophysial region of the brain and fuse anteriorly as a trabeculae communis plate. As the flexure of the aro art Sap her J a ‘ | gf acseuia ¥ r a¢ fee gatetes — é : aie - 24% bath 1c: Oo ale a ia’ 5 : ‘ : ‘ 14 neural parts disappear, the trabeculae become horizontal in position, except in that immediate region where thay are attached to the parachordal plate. Unlike the trabeculee in Amiurus, the Selachian trabeculae later form a solid floor in the craniun. The cartilaginous connexion between the alisphenoid and trabecular cartilages is far more extensive in the later Acanthias than it ever is in Amiurus. The condition of the cranial floor of Acipenser (Parker,'82), is the same as that of Acanthias, although! the fenestra hypophyseos may persist for a longer time. In the early Lepidosteus cranium (Parker,'82b) there is a large fenestra | hypophyseos which later becomes closed by the growth medially of the trabeculae. There is a large fenestra hypopnhyseos in the chondrocranium of the larval Polynterus (Budgett,'07), which, from its ellipsoidal shave is comparable to that of Amiurus. In none of these, however, have the relation of the internal carotid and trabecula been brought out. In all cases the nerves of the eranial series from the second to the seventh issue from the cranium above the trabeculae. In Salmo (Parker,'72; Gaupp,'06) the trabeculae unite immediately anterior to the hyvovhysial region to form an elonga- ted anteriorly extending trabeculs communis on the dorsal surface of which the membranous interorbital septum arises. The relation of the trabecula to the nerves is typical, but the trabeculae do not meet the alisphenoid cartilages in the medial wall of the orbit as in the Selachians, Ganoids, and Amiurus. Further comparisons of the relations of the trabeculae in other groups then the fishes are made by Parker and Bettany ('77), and Gaupn ('06). % ES: me (MG. ¥ P = ee Letre oder tetel tee re | fo imelte (ag i. ca yvlroltet ante 7 eat t dosent ae : - ey, nn ‘ cond eit to enontwaamos + 16 The otic region. The otic cansules at this stage are two large cartilaginous masses forming the sides of the posterior region of the cavum cranii (figs. 1,2). Ventrally, they are fused with the basal plate of the posterior cranial floor, from the posterior ends of the trabeculae to the occipital arch, and there is no gap ( basicapsular fenestra; Parker, in Salmo) be- Wween each capsule and the basal plate. Posteriorly there is no line of division between the occipit:l arch and the posterior boundary of the otic capsules. Anteriorly the cartilage surround- ing each auditory mass is confluent with the posterior end of the alisphenoid cartilage. The dorsal medial margins, at this stage, do not meet above the hind-brain to form a cartilaginous synotic tectum as is found in other teleosts (fig. 2). The vagus nerve passes obliquely between the otic capsule and the ventral end of the occipital arch, latero-dorsal to the pvarachordal plate. The glossopharyngeal nerve has a smaller and more anterior foramen in the floor of the otic capsule and is separated from the foramen of the vagus by a small bar of eartilage. The cavum of the otic capsule is fully open to the cavum cranii, except at the extweme anterior end where there is a small medial wall, bounding the anterior part of the anterior semicircular canal. ‘The cavum within the capsule is divided by three septa semicircularia into the cartilaginous labyrinth containing the membranous semicircular canals. The septum semicircularis anterius as in the adult (fig. 7) is a short bar of cartilage extending from the anterior wall of the capsule posteriorly to the midventral surface of the roof, parallel to the ee eS ad@ of fellste: toot off to eostem Sustawvhios abt ad giiog 402 ¢6 wotte oie gatsre? ovneee aanaeae! ‘ese YORt (etietiney .(G,1 .anlt) Migeee oie ,toolt feimeto 40ivetpeq sit to odes baz .doxrs faklotooo am ot exiveodant off te abe, “Bee ~temfae nt .sederd. paxteonel salseqpotead » aes on Bt exert yicolveico! .eteio [esed edt See eiaagne ebivetnoy eft bie dota Id totoce edt gaswier noketvib mre=zsie euplidxses eit yfroirevm .velverss otto edt bad So Bae totvetecy ofA dviw (asifined sipgere yeOoehaee eid? ge: tenteren ii Ber Laorob eit. ,eusijgeagor 8 ' eit. esi ae ne: .(@ .ait) atsce les veto, ai Sayétoet ke astoot 0 2 SronteesEidizas erro? of miiyd-Aris em evods 2am tom c bfvoceo Sito af? Wesried ca (90 CeHe MeV TEelt stieey. ea? 62 Loutob-oretel .jgie fatiareso ent to fire ‘os Bob seliews ¢ asc svien Inencyagtvedpeia off «ovalge of Bas Olvewes sito <@ To rool? stdiet Bemesghae. to tad ifeme a vo coney edt YO NeanaroY eff most page ei? ¢2 weco vila? ai olieqne sito est to one edt ei es uedrc emcw Das TroOivetdns oassl@ ait Fe sages iiae to tac ts red as eit guebbnod _ifew Lat am. 44 we “¢ Gebivii of el:eges ott mittiv apveo af? eee talve fiairvgdsel evoutualivise of? ola eltpipetiolmes aeaeee ‘ RIYOO est -tfoneo teLloovioiner emomsetdiea e4¢ Joixzesns +h “ad @tefe « et (9 .9it))§ tiebea- ede of ee eer at efoures aii to finw rebvetne eft ooet entignem. © 4 = Cae ee 17 long axis of the body. from its dorsal connexion with the utriculus, the anterior membranous semicircular canal passes above this septum into the anterior part of the capsule. The septum semicirtaularis laterale is situated at right angles to the anterior septum between the roof and the floor of the capsule, | but nearer to the posterior than to the anterior septum. The anterior end of the membranous lateral semicircular canal and the ventral end of the anterior enter the cavum cranii anterior to this septum laterale. The posterior end of the membranous lateral semicircular canal and the ventral end of the posterior, enter posterior to it. The septum semicircularis posterius lies in about the same horizontal plane as the anterius and makes an angle of about 120 degrees with the ventral surface of the roof of the capsule. The posterior end of this septum is continued as a medial wall between the cavum of the posterior membranous semicircular canal and the cavum cranii. The dorsal end of this canal passes posteriorly above this septum. The fenestrae above both the anterior and posterior septa are much smaller than the fenestrae anterior and vosterior to the lateral septun. After leaving the ganglionic mass of the facialis, the ramus lateralis accessorius of this nerve proceeds dorsally and curves around the anterior end of the capsule roof and thence along the dorsal surface of the cartilage, above the occipital arch to the body musculature. Im all this distance the nerve is unenclosed by cartilage, nor is there any indication of ossification around it. It is accompanied by a branch of the internal jugular which descends and fuses with the 5) ho n & P igi — vs te NTS tet mo ro tetns” at! Be ai en otat muterer == ) - afrprintoes sary a a e bee a a ro TS vote > Y tev 2 18 postcardinal vein in the region of the second vertebral arch. The hyomandibular cartilage articulates with the extern- al surface of the ventro-lateral wall of the anterior and lateral semi-circular canals (figs.1,2.). This articulation extends from the ventroanterior edge of the capsule just above the posterior margin of the foramen for the facialis nerve, posteriorly in an obliquely dorsal direction toward the lateral edge of the roof of the capsule. The articular surfacé is very small in comparison with the longitudinal extent of the capsule and at this stage there is no projecting shelf for this articu- lation. In a nine day Ictalurus albidus chondrocranium (Ryder, '86), the hyomandibula articulation differs from that in Amiurus, the anterior end being more dorsal than the posterior and in addition the surface is smaller and overlapped by a process from the anterior margin of the capsule, suggestive of the pterotic ridge of Polypterus (Budgett) in the same region. The hyomandibular articulation of other Teleosts and some of the Ganoids is in neraly the same plane and region as in Amiurus, this scheme of articulation appearing to be typical for these groups. The otic capsule of the Amiurus type is apparently derived frmm a primitive condition represented by the Cyclo- stomes (Parker and Sewertzoff) and found in the larval Acanth- jas as well. In these forms the otic capsules are fused vent- rally to the basal plate and the cavum of each communicates with the cavum cranii by a large foramen through which the seventh and eighth cranial nerves enter the capsule. The ninth and tenth nerves leavethe cranium posterior to the capsule 53 - te see a ten ‘+ bos Toltesns oarlt ‘ne tisw cba notiealvotian etfT .(2, 2.8 att) a Lene eveods faut siveaas sont te smbs ar ne peer .svred eh{atos? sdj te? nemerot edd 10 nigeem ae feusal ont biawod cchtoertlh Lastob yLleuphido aie me were ! ? >» grey ef soetwe isiyotiza scT <.olvnqed, Shit Yo Teen ontd Ye Selusqes afi to tnetxe [antbytignel ent addr noetaaqon nb epottas alrit 402 Borde Sxleovtord on a) saadd ognte whet mutaatoo-tbnods evhidle avywelador yab erta 2 at. * ei sedd wort aied2th soliatuo lias eLudtocewmoys edd +orn t aelaetecg ert cant [se 10h etom sated bane solvodae BAI y, a YW beqaalieyo boe usatleme et eos Mette exit aci¢thbe mtd me to evideegaue .alueges sit té slyte porwetna ont 0 nes | eMolges suman edd cl (tteshuh) avretqylot to eubha otdorsda fSna- | ed? tc ewes boa atscelseT vedio lo qolteiohicne salud d enutwlma al ne ocinet boe soolq Smet onteyiacen 68 @ q oxen? tcl [eolay? od of antisecqs aottaleoisus to emedoa at 7 aay ' vyivoevsqde ei eqyt sutwlmA est to shargas sive ont -oloyd sft xd batneeesae ~ poltisnos ewidintag o wort par efdgack Levial add ci boawol Bae (1losdaewed bas venkat) “onev Beevl ote acliscey otic edd annod epeds «az ew sa ¢ wy aotaoloummes dose Yo muyao eit bre etelg euad odd of vA a ' ots golds dawcuit asmeaio? egaak « ya ticeto muvos odd sd { eiT .olwecao edt tetne eevaen Lelnevto Atdate hii eluaqeo sit ct wiseteoq mulaut eft ovaeol Oe eae ° —— ta ae = — ae i’ é) j : 19 cranium posterior to the capsule in the Cyclostomes, but are in the same relative position in the larval Acanthias as in Amiurus. In Amiurus (p 13) these leave by separate foramina, the tenth between the otic capsule and the occipital arch, the ninth a little anterior. A description of the septa semi-circ- ularia of the Cyclostomes is lacking so that a comparison with the inner surface of the capsules cannot be made. However the structure of the ears in these forms is so different from that of the Gnathostomes, that detailed comparisons would have little value here. In the larval Acanthias the fenestra of communication between the cavum cranii and the cavum labyrinthii is as wide as it is in Amiurus, but a wall is beginning to grow from the line between otic capsule and basal plate, which will eventually separate the two cavi. Sagemehl, from his comparative morpho- logical study of the crania of the Teleost, says that their condition in this region is derived from the constant fenestra- tion of the foramen for the auditory nerve, rather than from the Cyclostome condition. The evidence given above of the presence of a wide fenestra in the larval Acanthias is against his view and in favor of the derivation of the condition in the Teleosts from an ancestor with a wide fenestra. The ninth and tenth nerves leave the cranium by separate foramina in Acanthias just as they do in Amiurus as stated above . The synotic tectum in Acanthias is formed very early by the growth of the median margins of the otic capsules, a condition not reached by Amiurus until very late in the larval period and then only for a short distance anteriorly. t « + a - , ain te yet) wi : tod " PERC a: 2 na. > ¥ Lz P “f Be , yl? ai hy as aatitimaoa fewral ‘edt at aan. wos rao otto extt ear asaot .tofrsdne elstet ae ase otec(oyd eit to alt , i) ® To 2 a lo sostiwe tem | ** eid ‘lo exutouray ox nodaodd sab odd +e a .eTten . sag feverel ond ar an) Sas iineto musvao ods nee ed ae = tod , Bi “Lu EMA at he efuages olte noonsed ¢ . 3 etvas ows edd aie bea to ybude Laotget . = i no Inet atid: at nod bone 10. mematol edd ‘Ye a - ce sttibaos omoseoLoyd - ea 2 eblw 2 to eonde@ai pF =4 Aft to 10vat at bas noni ofa na mont? adeoole? | ort ‘+ esldtnaodA at an bone mard oad ottonya ri. cam aotbem odd to diwor : re ai et done Rn 107 i = SR AR a ———— Se ee 20 The relation of the capsules to the basal plate and to the cavum cranii of Lepidosteous osseous (Parker,'82), is much the same as in Amiurus except for the large fenestra in the ventral floor of each capsule. There is no wall between the cavum cranii and that part of the capsule containing the inner ear. A detailed description of the septal relations is lacking. Part for part, the otic capsule of the larval Salmo as described by Gaupp ('06) is nearer to the condition of Amiurus than any other that has as yet been described. Except for the precocity in growth of Amiurus they can be said to be identical in all their relations, if the presence of the basicapsular fenestra in the floor of the capsule be left out of considera- tion. There is the same relation of cavum of the labyrinth to cavum cranii and the same number of septa semi-circularia are present and have the same relation to the membranous labyrinth in both forms. The relations of the ninth and tenth nerves are homologous in both cases. Externally the hyomandibular arti- culation surface is about in the same region in both. The synotic tectum of Salmo is very well developed as compared to that region of Amiurus. Except for the inclusion of the branch- es of the facialis between it and the alisphenoid cartilage in Salmo, the anterior margins of the capsules are homologous, although theprocessus postorbitalis is more pronounced in Salmo than in Amiurus. From these tomparisons it may be ob- served that Amiurus has an otic capsule which, except for several mbnor differences, is typical of the Teleostean condition. The Peragbrdal Region, Authors describing the origin of the chondradcranium in the Teleosts have remarked that the ; feesd edd od ag iveqao ont eh by. ei hale ae | ’ ay. exist). -eubsaec auo9d sok saa arenes MS VSO Toi Iq adel nwasiaa abae oa. se «Of sagan toe te soit tent tae +189 > Wests 5a Linero sme noveh bekiatebd A re t+ as teal - qquedh wi bedtas P 8 . oa mort derit radto qe f nas fon sleds te ki LOO ro eft at ante one a ? Ri svad : bos per . dant sod. a ‘ atod ok euoge Lom nod et es oatue nottee oc) to mutoed one e te no lget ta . aay at tatoat edt to. ° +f a solbvetjas eft Om. a2 eveassootgqeds dpucds La onutima alt arts omfae tea end exsoboa dactd willl BS OG%8 mad roan Lax +e 21 basal plate of the older larva arises from paired cartilaginous masses lying lateral to the notochord. St&dhr('82) differentiated each of these masses into an anterior and a posterior part, the anterior lying medial to the otic capsules, and the posterior behind the exit of the vagus nerve from the cranium. The para- chordal masses, as these cartilages are called, eventually fuse, vartially at least,with each other around the notochord, anterior-} ly with the posterior ends of the trabeculae, laterally with the otic capsules, and posteriorly form the base of the oecinital region. Concerning the parachordals in a general way, Parker and Bettany ('77:p.311) say: "When the parachordals unite in the region where the noto- chord still persists, it is by growth of the cartilage over and under it. The bridge beneath the notochord is very marked and becomes thick; the cartilage is thinner above, and oftem non- existent for a long time, so that the notochord lies in a groove _ on the basilar plate constituted by the union of the parachordalia In many cases where a basicranial fontanelle exists, the cartilages do not approach one another again, and the fontanelle is only Glosed by a bony gowth....... The whole of the cranial notochord is gradually aborted in most instances, and its place is occupied by cartilage; but in various forms a remnant is left as a slender string, embedded in the basioccipital bone or cartilage.” In the chondrocranium of the 10 mm Amiurus, the parachord- alia have already passed through the early stages of development and are partially fused with each other, with the trabeculae, and the otie capsules, forming the base of the occipital region (fig. 2})) Terry ('17) has recently worked over the literature on the parachordal region of the mammals and concludes that the par- achordals may arise in three ways; from a hypochordal center of chondrification: from a pair of bilaterally placed masses: and by growth and fusion of the apposed ends of the lateral occipital arches. In the 10 mm cat, the notochord enters the occipital “<7, Sa a * moztlt Gi D = av T 6. " t a4 -_— . (ies c .* ” q ) (sa! jaufbee sbresiootons j et sate ay * vital oper to eit of Labbom ‘git - toltes . : " ae tins odt bat wean 8 aa bes ttoda vas lesbe tud egal tir: i bobbedme ,% byodoataq t qam efeb rontoe U4 i} eoLttab ete te ri ix ? ons at WO A aig a ,eedo ae, ‘ » ‘ % _ 22 region between two laterally lying parachordal cartilages, dorsal to a mesenchymal sheet which connects them. This sheet later becomes chondrified in connexion with the parachordals, forming thus an hypochordal bridge of cartilage. This agrees with the statement quoted from Parker and Bettany, but cannot be applied as a rule for the development of the basal plate of the teleost chondrocranium, as the condition in Amiurus shows. The concavity marking the anterior extent of the notochord | on the ventral surface of the plate is continued anteriorly beyond a the tip of the notochord as far as the margin of the fenestra The anterior end of the notochord does not basicranii anterior. project into a fenestra basicranii posterior, for such is absent in Amiurus. There is no fenestra between the parachordal and the otic capsule corresponding to the basicapsular fenestra of Salmo. The sacculi of the inner ears have invaded the cartilage of the basal plate to such an extent that they have replaced most of it (fig. 8). The grooves on the dorsal surface of the plate containing them, extend from below the base of the lateral septa semicircularis to the posterior end of the cranium, lateral to the notochord. The saceuli communicate with each other across the anterior ends of these grooves, above the tip of the notochord by a transverse canal sinus imparis (ductus endolymphaticus, Wright,'84), from the posterior wall of which the sinus impar of This sinus impar lies along the the Weberian apparatus projects. mid-dorsal surface of the cavum floor and is separated from the laterally situated sacculi by a membranous V-shaped wall, fhe apex of which is attached to the dorsal surface of the notochord (figs. 17,21). It is separated from the cavum cranii by a mem- 7k © .34 eeusiittas: peta var os ‘2 ~~ T F cn ireer of ePpar wiiedit eéoonsa foliy teen oar, aie i : ; ‘ a v7 1: x e +7 , Slabsotdiestsaq sift At in coixenccs at bertirino, © Bpniosed . 7 : : él @eetae stat .onalitazass to exfhirte febxo sisocaywi ne esclt ma Beer ‘i Botorys tassevavs say @ oy c . ead Oo ¢ [ 10 UOC vei edt ter sit s. ae be pap & P 3 % moisnstoorbreto tagad ivaskoe seat ‘noe L[attaey (8 -@FY) tt to get —— , . a e on of > , i ice iwxe. mec? attatatnos ets ; strafsortobmee | ate rer por . poL .brodoed om ade | a= ; jen? Lo ehae foiredma eft ; mh a ~~ ] ' " ) te [snes ectevenst? | / gna : -e sutareqes sal code eld ro eoeltiwe faerob iio ; ; ifvooss Betas te ullerotat sfosite ek soldw to me ven el #1 (£8, 8 i vt. ‘ Fa 23 branous roof which continues laterally 1s the roof of the saccular recesses and is attached to the cranial wall at the junction of otic capsule and parachordal cartilages. Posteriorly, the membranous roof over the saccular cavities is replaced by cartilag¢ which is continuous medially with the ventral walls of the cavum sinus imparis and laterally adjoins the otic capsule. The ventral| floor of each recessus sacculi is very thin (fig. 8), but the posterior wall which marks the posterior extent of the psarachordal plate is thick dorso-ventrally (fig. 21). The dorso-lateral surface of this posterior part of the paracBbordal plate is separated from the ventral end of the occipital arch posterior to the otic capsule (fig.17), and through this space the sinus impar communicates with the Weberian ossicles contained in the saccus paravertébralis. The first post-vagal nerve or hypoglossus passes out through this space, but does not touch the cartilage of the posterior end of the parachordal plate which has narrowed considerably in this region. The relationsof the inner ear to the cranial floor has been described by several investigators in those forms having a Weberian apparatus, bat the descriptions have been confined to adult conditions. In a later paper, I hope to follow the developmental relations of the inner ear to the parachordals, if I am fortunate enough to obtain the proper stages. There is no evidence of segmentation of the basal plate at this stage, such as is found at the posterior end of the parachordal plate of Acanthias (Sewertzoff,'97). The distinct ridge of cartilage called the"Sattellehne” is lacking in Amiurus tc moltceut eds ts [few istnaso ait eft? gitotsze tect .eepuil? 185. ttteo yd besealqet et seivivac wiv0oose edt ‘evo. Fh VM guves et? to alisw fetsuer ent dete eilebben asenattcos etincev scT .efceqso otto etd eatoths giiexetal Sas iceman my > a — fil edt tod .{6 .2it) mtd? yrev at liveoss epeepoer dose to" Satraicetac sdf te tnetxe toltetaoc sal eiimee dotdw Ifsw 16 by stetaf-oevtob efiT .(f8 .zit) ywlisrtisev-c5etob Zoid? sf < es et efalq Lebaegesied ac o tte votteteoq eid¢ to | a. SG wiretacy adore isfvigiove oat %o Sine Lavtaey ott monk betax "> 64 Seqml eiumin edt eoaqa eidt daquverco ars , (VE.gtt) elseqao a gusecs ett ai fediiatisos seleotcee acitedeal ed? agiw acta ereeolsaocyi +o sytem {[asavedasg sere? ef? 61 Lond és @nelijtas edi domot Jun eeot td ,coage eidd dgvrerd?é gee oy Sewotten cas doidw etatic Istivedeataq off to Bae ge treteoq ‘ dota: elf’ at yldexos | Ged toolt fetnats ext of tee rena edt: rovmeiteles sdf | 6 grivad exiot esod? ot excteniteova: Laveves UW bedizoseb of Bbealtnoo aeed seved extitotrsesb eft ted padetegge nek ea7 wolict of egod 1 ,tevea tetal a “i vagoidtbaco # aba Ti .alebtodceten af! of tes tennit off do enoleiae haa a rob } a@ne25 Yteno1 ons stetds o@ cavone etsacdtot ‘he etcia L[rnod ari? Soltainemese to eonebive on st exedt | reveoo eff ta Bbrrot 8) es dom esata alae soniverh ef .. Ye’ 2Yeattenwel) 6eiddaped Fe etaia canst eeavies cl ada ‘on ofLodvet' edt bolieo epalistas te because the trabeculae do not become attached to the ventral Avacesé of the parachordalia, but lie in the same plane with them. Like the intereapsular floor of Acanthias, this region of Amiurus is solid, and, although in the early stages of Acanthias the notochord projects into the basicranial fenestra it is lateren closed by cartilage as in Amiurus. The inner ear relations have nothing in common as regards the parachordal plate, because in the older Acanthias the cavum of the ear is shut off from the cavum cranii by a wall of cartilage. As I was unable to find any statement concerning the later larval history of the parachordalia of Amia, I found it necessary to study a series of transverse sections through the head of a specimen: 19mm long. I have referred to the condition in the anterior region of the head of this same specimen earlier in this description. The parachordalia do not extend beyond the anterior end of the notochord, but lie lateral to it and are separated from it by a space filled with a stroma of procartilage cells. This space is comparable to the posterior basicranial fenestra which Gaupp has described for the 25 mm Salmo, but which is lacking in the 10 mm Amiurus. The parachordalia are triangular in cross- section and fused latero-dorsally with the floor of the saccular cavity of the otic capsule. A sharp crest marks the line of division between the two, and from the dorsal edge of this crest a membrane extends to the roof of the cranium, Separating the cavum cranii from the cavum labyrinthii. The sacculus lies on the capsular side of this membrane within the otic capsule, on Ps, ob. "ade ot hadoutvn nosed tell en “as dtiw enska ease oft nl ett duc , ee Yo moiges sii ,tsiddnecA Ro te0it xalijessbist ett / enidvanea tO eenots elaae oft «ct dquoddLe bow bios Bexetsi wi ¢) avdcenet Ietnetslead -dt otal etostosq oe evad euoiteie: «ac tent efT .sriuwiek of ee egalitzso gd f ' at esuseed ,staic Lebronowreq ot shxagex te sommen at 1 eis mot? tto tre alt wee oft tc muveo en? enisd nook ) easityseo 86 Siew & qd 2tneee amp eit aeiniechos 2tehetate yo» bolt of sidsan sen I Ba ‘ 3 bewot 1. .nigs to a2! irkhendoecin eit to Treteltd wipe on? agro? aac ivouc savevace:) ho selase & Ebote. ae. peteshone ey of Bbetrete: eves 1 dens gmet ~memtoege-@ $i telizuse semiceqs emes efdy to Ssed edd To mo tgpet xo brogas .coitqitoseb etdt Bae soltesos eft beoyed baetxe ton ob elf sbtosestag edt most betsiaqgee ote bus tt of (atotal efi tad . Steodegtans esigv .aliso egeli?cecotm to amorte « Agiw bel Lit oosqe's & Acids ertcenet [einetotasd toltetseg sii ot elfdatagmmo Bk si Hoidw tod ,omist o@ 28 od? wot bedisoseal ead ¢ ove silabtodoeteq ed? . .eruriek geet of? to stool sit itiiw yileerct-orvetal, Beart, bre FAtam ¢eéots qiede A .eleeqso of86 edt te ee aid? to egbe Lewioh edd most tie, .owp edd meswied Hote, sn lecnaq@® ,aulaets of! To Teot ed? of abaetee enmxt ie well tulpoure exT .Lidtutrydal enveo ot mort tineto am 80 O270 eto ciddtw onardmem ehdd Sovebie wale fo ,@i.260¢ 25 a higher plane than the medial ends of the parachordals. As the parachordals extend posteriorly, they gradually come in contact with the lateral surfaces of the notochord, at first by a sharp edge which gradually becomes blunt and finally concave, as it comes into closer contact with the notochord. The parachordals of the two sides remain distinct from each other however, and I was unable to ohserve a surface of fusion either above or below the notochord. The glossopharyngeal nerve passes to the exterior through the cavum labyrinthii between the sacculus and the The passage of this nerve in posterior semicircular canal. Amiurus follows the same route between the sacculus and the semicircular canal, but the foramen lies between the dorso-lateral edge of the parachordal plate and the ventral margin of the capsule, rather than in the wall of the capsule proper as it does in Amia. The vagus nerve issues higher up in the wall than it does in Amiurus and instead of being ventral, is posterior to The cartilage of the parachordals has a ereater | the otic capsule. posterior extent in Amia than they have in Amiurus. In a 25 mm Salmo, as described by Gaupp, the parachordalia}| lie lateral to and close around the notochord except at its anterior tip which projects freely into the posterior basicranial This fenestra is cut off from the more anterior fenestra. fenestra by a transverse bar of cartilage between the anterior The rectus eye muscles are inserted ends of the parachordalia. between the anterior ends of the parachordalia which form the lateral walls of an eye muscle canal in this region, the cavum of which is cut off from the cavum cranii by a membranous floor : ’ rum . ey, . ey 54 J feet a ee as > = rc — ad ats amare nil poponeomel p chine etiam eat mame waaly , @ = ‘> ~~ Pie ee f M iM _ ; padres ml amon qilepiera qYeds ,vitolte B04 haeixe abto: hey “a ‘ fer He? ¢ > 2) ae s 1 ‘ —_—ee | * — f . ~~ z Tite ciade 2 yd Deutt ge ,Sredoostin edt Lo BeoeTrEs +? es .eveconcoo vifentt bas ftacld senooed vsarhore gon iw 2 i + oa ow ters id ~ \-- ash roe Y je oo? isvreva 7 a shaw qht tolredt 8 etaT . onndé 18 3 : 7% enssTt?d Bs ud atte afte’ > Fade iooy ne . % : » Sass . sai ~ 1G OTE ant ic G28 » te ~oltetoa ed? neewted 5 of Th 26 (See Gaupp,'06:fig. 342). Commenting upon the parachordal relation Gaupp ('06) says: " Die Balkenénden verschmelzen mit den vorderen Parachorda- lia; die urspringliche Grenze liegt angangs etwa in der H&he der vordere Chordaspitze und entspricht dem (in dem Folge sich mehr verengernden) Uebergang der vorderen une hinteren basikran- ialen Fontanelle. Schliesslich tritt auch eine vordere und eine hintere Vereinigung zwischen dem Parachordale und dem inzwischen vergrossten periotische Knorpel ein." As noted in the discussion of the otic region there is a fenestra between the parachordal cartilage and the otic capsule in Salmo which is not prsent in Amiurus and the ninth nerve issues through its posterior end. Whether the foramen for the passage of the ninth nerve in Amia and Amiurus is a remnant of this or not, it is hard to say without knowing the earlier history. The saccular relations are probably the same in Salmo as they are in Amia, as the Siluridae have a specialization not found in all of the teleosts, just as the eye muscle: relations are peculiar] in a certain large group with well developeaé eyes. The relations of the anterior end of the parachordals of Amiurus and of Salmo are homologous in that they lie between the otic capsules on either side of the notochord and are connected Primitively they are alike, but enteriorly with the trabeculae. specialization in one form in connexion with the ear and in the other with the eye have made detailed comparisons difficult. The occipital region. part of the occipital arch forms the posterior margin of the As remarked above, the dorsal posterior fontanelle (fig. 2). The occipital~otie capsule fusion takes place above the foramen for the vagus nerve and behind it the ventral ends of the occipital arch are fused for a short distance to the parachordals (fig.21). Behind this D -ab 4 one faqinev bre (Se10b déod vad eevee, nclisnes eti¢ Hoidw at sao ylro ait oie sede ta a allanes eff .alizaiqe muvee ed: aldtin sett soon to eflaw ehfe sft of Laretel bre Lenvetxeteii-tiie oneitto -Leveb [Lew yrev « evad gexti oft sqeoxe T1A ~eseieaa : ie tilanotsibbe na yilever bre bess atflaxetal bite dititwel oni slavebiqs eft of yilsesch ebeasong dobde_euued treanve il ace ¥ evien Lapav-teog tetlt ons tc abistéte byean od? “eta and fextuev eft hd eofosu ods 03 ylemplide sbitsseab( Ly ies Baa olbits tebliwds add to nage tne sit noowted ybod oad 10 fies tow aS prety te etten ([azac fnogy! attends oats ov efde risques et ne aldt eidiaty on svar etnampse efoagm owt.sed? oA? BGuOTR ¢ dye a bejJavienat *ta ednomace slocum céoot bea batd’ edt sno ave 2eovien brbrit bie baovge sdt Io. eefsetob ined tontsete- ck, = 4 eomai edd DID ap bustceh eswisa owt seeds to ines esianetal bee neonted eiyielysoeum soit of .sviem deat? ad te ali | -ifbily tebivede sntqeiéveb efi + 5 .(12",26', 38") idemeyse .(T8") avedneged te utow edT- lt 2 may .(30' ) Viesdaswse .(L0")nwiog .(88") andes ¢(£0") aehwony ef? Yo acitaler ed? co atedto bua ,(Te") nenu tide «(88"). oatan qd bewetver need cad nolnes iigtooo ed af Seed Bas west tl gota « es wantidxh) Yo Axon oct coxbeatiqns On +{80") qa . ne noltazeup eli! tc galbaatedebou oft vod aobdoenth tdgta eng | obisenet ect ni Jaetetal ic sleiog ait Yo espe of Elteted ~otee et -(VO') ategntedsia i, ‘eoleT offs to Aimays edt ,10ntdu atdd od pokbrooon py a LP @: fi pbb arione ,mvlwetscelet solftedna one | rt i fii cia’, aallooe Se aotfodlytels ent ..cotottnl ws a e. a a Al sonsue eft yd bern oxa anes end of ao ber ‘ Hiquers taedsTtLh eat at afnadscen Yo nace? went falaatocen oft bas cuyav oft dtiw fae aevion (é] wiowss ant ofiitinw bobw(Fst entm sed sioted conte g Helles sia hebulout ce ebvvoe efodT be es ows cfm Sebtett tont«s? of bus geveon “Ledne muldetooes olvematomotorg oft nt \bé2olode tenth 3 -siemizus edt ot exorit bua sored "eledtgtoon" Red saa 8 . eptaloxs 6H .sevisn “6lailér-ottatsoo”’ end ob i ea? mit seviten eset to sometaecas boa vedmwe ot nwt ~waetintese enel ‘to stom lo ¢lusset Ssdv ne aque Lambe ¢ Oifegayzetb ald ol .2etimos to yogests Sas sheds deal acd .amattnale2? edt ot nottlbnoo ene Ia odd tae "2" sottel off yo botnsestqe® ek evien Daa eeriell? iwéiisic of! Io seven cdi feniqe sext sett? oft to engolomond ade (tar we soto tom ~eseceleT ,icagia ,chicasad ,éLatioesolon cre tine lite sinemademtkis af3 ld fclwey Luttetood as peer idesyov te wiedeun tacte?T th add reunite og a a —— on Ae ey ne tee 32 and segments take part in the formation of this region, so that the cranium does not end in the same place in all these groups. The cranialevertebral complex of the Amniotes includes three vertebrae and the hypoglossus nerve of this group is the result of the fusion of the three nerves corresponding to these three vertebrae. He says, that in a general way the auximetameric neocranium of the Teleost agrees with the Amniotic condition. The nerve formula for the occipital region of the Siluroids is b-0-4. According to this view, the first post- vagal nerve of Amiurus is an "occipito-spinale" nerve and corre- sponds to the second free spinal nerve of the Selachians, which the Arabic numeral represents. Thus, there is one segment missing between the paleocranium of Amiurus and the auximetamerid, neocranium, and another between this and the first free spinal nerve. This method of reasoning is based on Sagemehl"s hypothe- sis that in the Characinidae and the Silurgidae, where the Weberian apparatus is developed, the claustrum represents the neurapophysis of a rudimentary vertebra, and that the nerve which originally tame in between the claustrum and the scaphium is lost together with the muscle segment. I do not regard the claustrum as a rudimentary vertebra, but as an intercalated cartilage, developed in connexion with the specialized Weberian ossicles. The scaphium may be the first true neurapophysis and a modified representative of this part of the first vertebra. I hope to get further evidence later, for the exact somitic relations of these parts in younger larva than have yet been accessible. For the present I accept the hypothes#s: suggested by Kingsley ('10) concerning the relations of the occipital an — ——<—— ssid o2 solget elsit Yo ac hiantot - saquoag eaedd Lis al svelg oman eit at be eeiit esbylont esfotnsA end) Io xofemes . divees edt af quoxwg etdd Yo evten asioaciagentet! eeudt event ef antbaogestioo sovisn eendd og to noise olbvemaseomixea od¢ yew Laaenen « of dade .syee eH af smoltiones ot¢elams edt tslw cesigs debeheT edd | eid to néiges Lattatove ont: tod emack: renter -Jued fash? oft .wohy afely of yebaododA 45-060) . -eTt0o bee evisn "“eleniqa-0iiqisse” me et evs ede olin (enatdosIe® edt to evren Intéts otk badsee Gd Ode a dwomgee,enc ef event ,eud? .etnesotées Levemes ofdeth Dizeratemixue sit Hoe evaytwA ‘to omiggsooelsg sit aeons i aie mn Bs — —s — nt - a a faniae esa? Jarit et bos alilt moonted tedtone bra, ATIC sertcqys s*Iramegee nc fhoeed al sotnogaby to borsoat etde cova” odd stede ,oabloh will eit bo eshlabseaadd edd ot saat et ed etoesatge muydavelo ait .becoleyveb st CuOGTHRTS 4 fi i evren eft jadd fos aidetiey yietnedtiet « I éiuydqoqatue muiciGack ef! brie auitewalo ef! oeestad at anaes {i fentghte eae eis biage: Jon ch I .inamges efoaum elt dttw tecitegot deol ak besalsonreto? na es sud .etdéetsoy yrstnomtbys Bee muasevate Gaiseden bestleloeqe odd dtiw actxenneo a2 heqolaves |, énalke , bana eleyeqoqewon ouvtt Jarl? oft ed yen moldqsoe ed? emiceinev Jer7ll oft IO freq elds to evitatnesorqet beltibom ‘s - P Gitimoa Joare on! 10% .190al sorehive isdiwil tag os’ eqow'E | need Jey ever nai? avial tepnuoy ot aduaq seeds %- onchsaten, 4 begespywe @toadtoqyl eft tqoooe I dneaeng ott aoe ‘sefdteseoon : \ > fasiqtooa mit to anottalen sit yntaweénoo. (on) RI Rg ee = _—— region in vertebrates, where he says: " In the vertebrates there is a continuous addition of new somites at the posterior end of the body as in the arthropods amd annelids, implying the existence of the equivalent teloblasts at the posterior end. The assumption of budding zones at other points will explain other features noted. Such a zone in the occipital region will allow us to explain the difference in the number of cranial nerves in the Mammals and the Ichthyopsida and yet allow us to accept the homology of the occipital bone throughout the series. The additional nerves are thus to be regarded not as transferred from the neck, but as new or inter- calated structures." Reasoning on this basis, the first post-vagal nerve of Amiurus is a new intercalated formation, possihly associated with the second somite. What part the first somite plays in the development of the occipital region I have not been able to as- certain, if we assume that the first dorsal muscle segment is th that of the first metotic somite. In the larval Salmo, Miss Willcox found that there were five segments between the poster= ior end of the otic capsule and the first neurapophysis. Two of these disappear very early in development and have no trace of nerve connexions. The third has a rudimentary nerve which atrodphies early. The next two nerves innervate the next two somites and issue from the cranium between the parachordals and the neurapophysis of the first vertebra. These are later en- closed in bone and leave the exoccipital through the same for- amen as the hypoglossus. Flrbringer's formula for this family is b-c-4, thus having one more element in the occipital region than is found in Amiurus and adding another vertebra to the cranium. The myotomes which disappeared in this case were those which took part in the formation of the protometameric neocran- ium, most traces of which have entirely disappeared in the Teleosts (Flrbringer). But here in the larval condition, there Tdoled | de At ade oan . ale hae 8 a . q ene at b bénwebatis oat atatexe ebt I ed? bas eaod ‘qisoo erie to ad of e%e BeVIon cnr ee e¥sinl to wen os 3d (took efd mont eked de evitea [epav-seoq texit edt . plead eis m0 36 betetoosee yidteacg. .cotismiot betelsotedal wen a et as - eat at eyelq etimes faxtt eds sSuaq sadw od inion hpones 8 a p -2#2 of olde nesd tor oved I motget fatiqtoso edd To vane os a a .: ‘ entm ,omiag® Lavisi exit ai .edimoe oitotom se ) ie . ey , oan snail alaiineemeie ~~ ee a nn a - “ a gee on —_———— eae o4 are more somites related to the occipital region than in Amiurus and yet the ultimate development is the occipital bones. If we assume with Firbringer that there are more vertebrae in one case than in the other, our homologies are no longer such, but are analogies of structure without any natural relationship. Even within one family it would be possible to have an exoccipi- tal vertebral articulation which was not constant, allowing for the attachment and detachment of vertebrae. If we assume that the first vertebra, however modified by specialization remains constant bhroughout the series, and that the changes in the occipital region are brought about by intercalation of parts, th then our homologies and our basis for natural relationship are maintained throughout all the groups. Jordan ('93) in his work on the relation of the number of vertebrae and the distribution of fishes has shown conclus- ively that homologies cannot be based upon numerical sequence. He counted the number of vertebrae in closely related species of Teleosts from northern and tropical maters and found that the tropical forms usually had the smaller number. The cranial nerves and bones were constant and yet there were cases of intercalation and excalation of the vertebrae. Schauinsland ('06) has also shown that vertebrae can be intercalated and that myotomes, nerves and blood vessels of the body cannot be serially homologized., There are various 2 degrees of intercalation from the prsence of both arches, nerves and myotomes, to the absence of one or two of these elements. These facts give conclusive evidence that the nerves leaving the cranium posterior to the vagus cannot be serially homolo- Ba stenod Lastetooe edd et Jnemqoleveb otamitiy oi? Jay, ent nf saidsisev stom ets exer? sand gma Jin omy | duc Howe Hepoel on exe eolgoLonod wo \reddo edt ak: cd a -olHencivater Llewideq yas tuodsin susoutt a bah Dy Bus P -rqtoboxe ms evail co? sidteseq ed bivow tt yltmat aa: fiw net 10% geiwcile ,.jmatence Joa saw doldwa céitelustien’ Lat “1¢ é, & sets ecwese, Of YW .satdedsev to tnémdoateb bas sojomsions se actedey actéssi(stoete yo 54) ilbom reveworl uneaa et edd mi eSyaahs off tect bnue .setiee odd Syorggoumla Sa? ,edtaq to nofvelpo mint i syoda diayord ete molges Letts ove qidenoitieaist lauder 101 elasd mo brie oe ss nib —_—s i - a 6 " € ® to vee 4a ,Molgevtt tase eiel i txecte adt to Prog Cree a 20% —_a itiv colichooltts ath weted oan, oly cem 9 se -eirreqac cific sedi mEiKXd Ga eueds ecict ts tresein ote sehod Teivetege ox? . wofeg Sue of roltetcod evucti svitcetinbo egondht Te pteode ber . * eaefivires so luee he me SO Woliet esi diw dnott cf beat sad epsiivise & ‘Tedeet fieq wetiewae ei! wet tewol evcunituos & aah ebia ot 0g TO 3 , _s is aye. pi Pent eitolveten sod ,levixhritfcs fee wetmels we egei teres res ’ Be Se0cc ig diade & ai etand o¢ethess ott aeiw nottal sold xe otek - emeb Latdnev-onv0d eft Ban dontave Inoaés ry. mroyed yitoirern: 5 fis ra -aealits vi! Yo ooetq £Lfame & . 0) com live thipotdan etatbanp eat petsuso enitaluy off \bevqotrs Lialqooelel) srtometegmeaaae al — Setleje siods bap cod etotiaup-ogytete eft A iw Speemkenen et nel” os .anecoiq [pte 1 and go slapodart odd Be eoal wes tovoael | af Sense «oven ¢! ba» sovriws af ob tsety Ge fem BE Sena 0% Steg e879 aziw gees? stud ,UPesoTq Kilomisvedom ott dtiw tus palatina of the opposite side forming a complete upper jaw. Since it is supported by the hyomandibular posteriorly and touches the cranium anteriorly, this type of jaw has been termed amphi- stylic. By dismemberment of the primitive upper jaw of the Elas- mobranchs, the condition of Amiurus is brought about and the pala- tine part of the arch is separated from the pterygoquadrate part. Steps in this process occur in the ganoids (Polypterus) and in the teleosts (Salmo). In Polypterus (Budgett,'00) the palatine is continuous with the pterygoquadrate part as in the Hlasmobranchg but has an extent much greater anteriorly... There is no palatal process as in the latter group and the anterior end is attached to the ventral surface of the nasal capsule. In Salmo (Parker, '72; Gaupp, '06) the palatine cartilage is at first independent and secondarily fuses with the pterygoquadrate. It articulates with the ventral surface of the ectethmoid process and at a point anterior to this with the ventral surface of the solum nasi. The part of the palatine which articulates with the ectethmoid process is club-shaped and larger than the more posterior part. Thus ther are important differences in the shape of the cartilage and The wider the manner of articulation when compared with Amiurus. separation of the palatine cartilages and their articulation with the lateral surface of the ectethmoid process may be the In Gymnarchus (Assheton, result of the depression of the cranium. '00) the palatine part of the palatopterygoid cartilage is fused with the ventral surface of the cranium, thus differing radically from the condition of Salmo and Amiurus. In all of the forms referred to above with the excep- tion of Amiurus, the quadrate is a thickened is a thickened mass ke ~ + ¥ ; ie a gates? obke | . a weet Tegqes etelurce 5 30 oe efmot bas ylroitessac selndibasacght ete : =higme Bemsdét mood cad Wat Yo org? eidt seecleute an ) eeald pat Xo wat tecas evitinizug sit te rinsing etieg eit fan trode tinword al anrterimsé Té no tet hires ont | re ted evetherpopytot« edt: mort faterstee gt dove Gir ae dene at bas (earretqefol) shlothe sit «it Tee ceenoay elds mi 3 emidgaled ed? (00' .dté6a6b08) aniecayto® At -{ omthBBd secon Ohaidorwsals aft il tua, etrcbsinlogereita) walt iv tw eprocmet ein Jae fatgieq of ai eted? ..yliblivsias coteetrs Kee tietxe a8 6p beilsedes ef Sus tolretats.682 fos quete wetiel ai ae ae 500 ,tearsi) omfet dl .civeuso [ener sd?t to eontehe Baviiey ia tmahssaqeial gevit ts af aftites etiveleq eat tag vaca 18 rf Setaidetizs sl .oterbavpogyeeta aft ddiw eeest witabaoove Bi Suiogd 2 $s Bas sedecot: Htomndiatne okf' to seatade Lertoev ext Hi iw oat .lenea molos « soxntren Satinev SAS cdi gals on rotiede Btecetq blondsato itty eolefoohiva détew sebfetag ei Se tt ead? ote freteoe a ois sect stenrel S88 scat Bes easlittsie eit to 5 Sudd ol gsspretehtrs saateount ors Wed Pehle eat .eivinimsa dtiw betscmos nakw gabee tu nits ‘Yo asin Roiietvetice rivdt bow Beas! (ties emrtaiaeg ext ‘bo norvereded ” eid od “ " oe eid US antdaten exec eft att | 6 treq “tobreteee fevtnov edt HO anhre ed Bb . ) sterberp ont sexo Litres &"favoe! to sottetooktns 6a 70? 08 ev Io seed? of sncitsier avi a} = Lasoqeet too cute 20 a Bplcdliaemeyd ett déinw yltobtetenc-carch Beout el tod : a -dmaebh sf egelitrss talogiinemoyi edt epuetaqgios ai . "em O@ie giisertoh anivet(notiére eine hbeddule e¢i To ono ee Be toitessou giulibiesceb teste eft bas elveqee olito ty to stow 6 -PimA onifsU .enelhtreo starbarp edd ,aott ef ungo a J 8 Siteivcibusmowi txrmet ait eholone ton eeob 24 omtab has é Stoayte?” Ane satistag edt [Se' oat e¥ meV), aden at rf 7 . p . P ; 7 Ned ¢ “ fnwasv od? dvivw acitefvoliw na sever bee beast eae vost : + Hf | ee! : a “ € -OV ods amrol sedval ei? aI .seeoote Bhomddetes éf¢ ~ ¢0 -sevaqiol mi nadi adivsiseolite to tnetxe tedsera 8 aad ‘te St) sic tetsen si evren elteledibasrogd edt yot meastot ede - tad Si #f asdid eixrelmk ot onal itereo edd to enbe secre tedao) tefitst sown eell etetbagp edt redtal at 4 Setineie & hoe ,evisimd oft seob st awed? als dP beeecorgd eit to fod - tz ™* bis tolredns eit mort tt wofed shaseseh easooxg owontaatits 89 OS Goide tremefe ottosiamys odd at oti -slodtinemoyd ect +. x See ber eat dtiw beect af ty wicgiok of Inebacqeiat tnwet | idrse to esem gefudhE Sioa ovoTbagp em butited 4 unvot eeeds Do Efe at | as 4 enottarys bas oqade Ist 3 r q f ¢ ‘ GAL warts BOA | eysoneo 50 sytetmA gt a cor on” esa tbe a? Snayeod etvetore bas nelweyege art bas epeliPteu ef) Ic ooetwe Leerod pitts ac bawot pbecord th 40 is well marked in Polypterus, but does not project as abruptly as in Amiurus. In Salmo the cartilage has practically the same size from anterior to posterior ends. II. The Skuliim of the 32 mm Larva. The description given in the following section is based up- | on the study of the head region of 20 mm, 32 mm, and 60 mm larvae.; The first two stages were specimens of Amiurus nebulosus (catus), and the third of A. melas. A wax model of the cranium of the 32 mm stage was made, as it gave all of the typical perichondrial and dermal ossifications at an intermediate stage in their devel- opment. One side of the model was left without osseous parts, to facilitate comparisons, as is commonly done in modelling of this kind. The 20 and 60 mm stages were used to supplement this. | Nearly the whole roof of the cranium at this stage is covered by either perichondrial or dermal ossification (fig. 3). The former sre derived from the ossification of the perichondrium of the chondrocranium and the latter from the ossification of connective tissue membrane external to it. Sometimes the two ele-] ments are intimately fused. Another type of bone development may be mentioned here, the ossification around a lateral line canal. The development of this type of bone has been worked out in detail by Platt ('93) and Klaatsch ('95). The roof is no longer widely open as in the younger stage, but the fontanelles are limited to narrow slits, anteriorly be- tween the frontals and posteriorly between the parietal part of the supraoccipital ossification (fig. 3). The nasal region has an internasal septum which has grown up from the floor of the eth- moid plate, separating the olfactory lobes (fig. 22). 7 "s Z » =e ie. Lae ; ae — - - Pen _ ee ‘Saul a ea teshenm ton Pace id, oh Ail omee sit yEieetvostc esr epeli¢xes oft sae go -Bbae <0 Pre deed ae cesta “4 ; .erral am SE edt to «Re caee ott my rae =u ferred si moitoos. smivwoliot ed? ab sevig nottatroseb on, oF @avisi am 08 bae om Sb ,om OR te nolget beed eit to ybote , \endao) arsoincec aoxeins To ensuloege stew eegets. ows smi ‘ of? to suigeto edd to febos xaw A .oeiom «A to* baidd a fetthhofotteg Lsoiagt oat to, iin eves 22 ge ,Sbau esr egeta, : a vier, po i 7 —feveb tiedé at axate etalhemratal ce te exottsphtreeao . et ,edted sutteeco tgodsiw ttel sew fehow edt So shia pat ata gidd tc shilichom al enob ylaoumes ef of ,ssoatzeqmes etet iit 1g iS .e2ad¢ tremefqeyo of bers o198ew epeygste om 08 boo CS edt n at el egats eide 20 awigats oft to toot eLodwa odd yfrecll , oth. .ait) woivesitieso Ipmreh 10 Inithnodolreq testie “a Os me i Bui chaos ol ter eit to mc itagiitiaso of? mort Beviteb ous tee i TH Heittecoltineo of? notl setvel ed? bae nur inetootbaode! od -efe owl cd? sealiermvu= .¢i ot Lantetce sna tdwoem, exealk? evite a wy SieesoieveS excod to sayt tedtoni .beast vietamhtat eis sine omit Ietetel « bovots agitacitiess ed¢ ,etod besaivoem of Xa iso Detvor used vad ened to ecyt eid? to tnengoLeveh eat. as ) .(0@') doedeealt bas (60!) Oteiieag Ihages, a ,sacte teqano, ed: ; ieqe Ylsdlw tegnel on et Teer eg? a -e¢ gitolcctne ,aetilo woreda ot betimil ess eaeliesadéaot edt. us =¢ duag Letvelteqn eff neowsod yltolsossen Bes sistnort en? | -\® .wtt) goltaoltieso fet igloops ~S?6 eff TO tool? et? Meosctl ac nwotsn aed dofde a tgon Ise ar" . * - _ - > — re ~~ a - _ 3 sedol yrovostlo edd? gutteradce or 2 a el — & of i fl saat > 41 In all parts of the cranium the cartilage is more massive and there are very few places where ossification has proceeded far enough to replace it entirely. The fenestra hypophyseos (fig. 3) ts narrower and closed ventrally by the elongate para- sphenoid ossification (fig. 4). The cranium has grown 6 mm in length since the 10 mm stage, and is relatively much flatter. Detailed descriptions of the various cranial regions follow. The ethmoid region. This part of the cranium differs considerably from the younger stage. The olfactory lobes are no longer in the very anterior region of the ethmoid plate, lateral and internal to the olfactory foramina (fig. 30), but lie farther posteriorly, and a massive internasal septum has grown up between them (fig.22). The foramina instead of lying in an antero- posterior plane parallel to the long axis of the body as in the 10 m stage, now lie almost at right angles to it (fig. 3). The ethmoid cornua formerly wide blunt processes separat- ed by a slight indentation, are now narrow and pointed, with ad deep notch between them (fig. 3). The floor of the nasal fossa (fig. 22) , the solum nasi of Gaupp, is wider and thicker than in the 10 m stage, although even now it does not extend as far laterally as the palatine cartilage. The ectethmoid process (figs.3,4) described earlier as projecting from the cranial wall at the junction of the ethmoid and alisphenoid cartilages, forms an oblique ridge in the cranial wall above the orbital foramen (fig.3$) and the anterior part of the orbit. The foramen orbito- nasale is more posterior, evidence that the cranial parts anterior to it have elongated. Theil cartilage internal to the ectethmoid | hey . -evdeeest oxtd st egsii izes: ond setcaro Sum rea behecoorq eer mottesttieanra, éresiw ado sceeydcortwd attrenot ei? «yfetiine oe peer aes «stsq eteadofs oft yd piletiney foxofo SRR, reworTen mi me 3 awotn ae mrifeto eff «(2 nit) motive we@dnit doom. yloevitsetiet ei Ors .wolfot @mOiaéi ([sikaTS arotcey sit Te enol tqtreast bos wa erett?ip evineto alt te dteg e& lil mg ipet Looees, oat ie J Om ota sedel yrefestifo sit .sgate swegmoy end wort wéers te i bd .. is Lesetel ,avalo biomite git a noiset teftatrs [rev etd mi togaol ee Senvist eff tad . (02 .B!f%) animere®. <2 oteat fe eit ot Lemmmtit goeewied gy IovoTg ean mute ae foagante time evievas 8 bas eel w - -ore2Ne Be ni neltyl to Beeten! poaelees edt te ygi) edt: _ 7) ¥ ed? alt es thod ait to pixk «ool ent of FIeliareg ‘ah (8 ghd) 22 of eoigne dipit te deemis ozs ron gets : -Jarteqese ReBBODOTC tovld obiw vitromrol apitoo btondis agt an as Be idle ,Betoleq ben wostan non ots ,gotdetnabas- tigi ia 8 ube rm rl seect [seen edi to too lt el {S .git) Mets roomed dovon ceed a = qi ? tedeid? bar tebiv si ,awwed to bean mics oft , (es +) tat ce bretxe von b Jf wom nove savodtle 2846 i OL edt mk rae” Beeoo ty Shimfiestes eAT .egalituse saftaioa ‘ont ea wilessteL ae" | ie a4 2 Ifew falceit i? mov oailvoelota ee tel inzas Segieeees (48am Seyret ,eenalier gedgetfize 5 Slomdte oft to adivonegt oa meantet Lad'dc ic avode [lew letarto ens gt gaees in : -O¢icx0 dewetsl est idxo one ‘ro drow tolvedab emt Bas’ (0Re “clvetade G@rad [nleerto onc lect seunehivs Biccuisetoes ef] of Lantota! ons lit wasted 4.2 process in the dorsal part of the cranial wall has grown medially | and fused with the internasal septum to form a rudimantary ; tegmen cranii (fig. 3). The anterior margin of the fenestra hynophyseos formed by the fusion of the anterior ends of the trabeculse lies mid- ventral to the optic foramina (fig. 4), and farther posterior than in the younger stage. The orbital foramen is in approximate- ly the same vosition as in the younger stage, bu the posterior dorsal margin of the ectethmoid process now lies above it (fig. 39). The foramen is limited by a perichondrial gesTPiSabion between its ventral and dorsal margins, so that a small aperture is all that remains of the larger foramen of the 10 m stage. These ossifications are continuous anteriorly with the perichond- rial ossifications on the posterior wall of the ectethmoid proc- ess. A perichondrial ossification on the dorsal margin of the olfactory foramen encloses a branch of the internal carotid art- ery, as it passes from the cranium to the nasal sac. The olfact— } ory tract is entirely enclosed within the cranium from lobus to the olfactory foramen. The development from the condition in the younger stage, has kept the lobus close to the brain, while the anterior end of the cranium grew forward and pulled the olfactory organ with it, resulting in an elongate tractus olfactorius. This stage of &he development of the olfactory relations is comparable to that of the Selachian type as has been pointed out in the Cyprinidae by Sagemehl ('91). : cle a - Ree ental aiae ae = = " Urntmam be a omtot of minteree ae eae ote gee) nee Boatot seedy dirocysl stvesnet of? to ahyiam Trias, wt § «Bite eeif e¢iroedstt ef to ebao to ttedme oft to notes’ asotieteoc tedixet Exe ({2 soft) asimetot ottqd ode we ere gamitetaqs cf 6i memevot Indidto sail .egete tegaroy ante ia ,Saots tepmroy edd m2 ee motiiged emae dt yt tL svode getl wou stoltetece anv’ ud sy '), i epovag btoudtetoe edt to abyaa Bae bo piveckiitess IsirScofalte¢ 8 YY! i betinil sf memetot ed? .106G Sivtzede Clase 2a gadt oe ,eutgiean fsetoh has inrinev avi mee -ene@h fn OL eit to nemaiot tegrel aft to salames deny" L i abnodolase ore addin vitetretue acecnitaes ets ano it aot 16B6 6 " —S0%¢ biomitotee eile te ifaw toltedecq ed? xo exctemot treet ii ' edt 26 nlevam Iewrot edt ac moitaotticeo Letxabaotolttorg & —@¢5 Bitosao LIentetat of? %*0 donatd 2 esectone memetet er sfeetio eff .cee inean ed? of auineto odd mort aeeseg of es a“ Of andol mort mrinats ed? aictiw Sesotone vleritae at tease at pottitineo ed? mott ¢aecucteveb edT Osh TOT soteetO agut ogee TORO oicato eft to Bie tobset ivisse:r ,ti dviw aente Bae ; ek 20 egste afaT orl TOsOaeTe a at [e& eft to tad? of eldateqmoo e2 “oF ue eabiniiuey edd ot doo botulog Or efidaw .ntesd eft? of otolt. srdol oft tqad | brewio! wer aevort: eieGacle ae at at Trotostio ef 6 Iaomolevetb aa eye? mal ao o(fO*) “ Ceftarenat 43 The dorsal surface of the roof of the internasal septum is surmaounted by a pair of dermal ossifications (figs. 3,22) which lie on each side of the median line of the head. Near the anterior end of the cranium they fuse to form a single median plate. The anterior ventral surface of this plate is fused to the underlying perichondrial ossification by trabeculae; poster- iorly there is a layer of connective tissue between these two ossifications. The paired posterior pieces of the dermal ossifi- cation interdigitates with the anterior ends of the paired frontal ossifications above the posterior end of the internasal septum. The dermal element is the anlage of the dermosupraeth- moid part of the adult hone, and the perichondrial, the autosup- raethmoid part. | In the 60 mm stage these ossifications have covered the ethmoid cornua and extend laterally above the anterior end of the nasal fossa. There is also a perichondrial and a dermal ossification on the ventral surface of the ethmoid cartilage, which, though not apparenttin the 32 mm stage are well developed and fused with each other in the 60 mm stage. Both dorsal and ventral dermal elements extend andteriorly beyond the cartilagi- nous cornua and fuse with each other forming a sharp anterior cranial edge, notched medially. A small pocket is left in the wall of the nasal fossa between the lateral edges of these ossi- fications which persists in the adult. The anlage of the premax- illary bone is fused to the ventral surface of the ventral dermal ossification. A thin flat plate of osseous tissue derived from the ossi- fication of a membrane lies along the lateral margin of the - P,: . nk . . Aenean an Site ft yeah > e ray, 7 eapie wode ot © aivoitse fetelea ed: ot tidro eit to bae foLtetas ad? mort e6e eonle mexkae sail Holierisiaco tetricododye? ..@ alt) et omit) ,@ostuys telcolitts aidy Sus. is saBDet” biomAted oe ent” odd and? Bottteecnn bcvawt' thon! ctrtzve eft ted , 7 oad od : .cdatsc faerrsh Boa otse dtod bed ened btomiteyos’ emf So eed -S27) Lamtise!l ots bac leona ods ,concd entl Fetedes ‘ow? ind ne a nO engct [Hear efi to Toor eal To Joe o geet aA ad, 5 edss2 bettierc tigierte gaol sat | om) Sereg eee, | sebEe wd 21 mowt betetecce Sa> btowivertage ait od folietst poibe 3G moitieqo See fae toi rodtea aid efibetanos ti .eoege smsot ely to ceeoow od = -ingeo Y ened «Byer aE Lat teroetiee | tée*} dtacs gd SDeditsesb ceed asd =kAs ee ened es dome to: ever! vietsecenuy ef tt Sets oe ,{3@") docrsas b O29 To sigtom Letedai-ovisevy odd teen ae Cemtio@l od? ae ed? Yo fine toltetues off eniataco baw dese’ Laven eit to Yor } et enlisuc tefrsnetxct 3 . Lorne vtounse-oxeihet {at 1érodme goifneicumeurs 10? sedotd owt otnl Lanen odd Be! nobel ae eee nb” ed? agviw sefeciurt? fi yUluoitetjsoa-cptgey sere out aste hi © .a22) doisrec Lat idtonrtsat’ ot 36 efotese colrediie | “me Lagtes ads ot onvela OMNOD ew benetset at ee pr bue- v2 ett soews of ; ‘e ) Goltaoltteso entéaieq ev BPicagers deine enalidtec oid yd bemrot sf eeeee Levan edt | 45 the nasal barbel (fig. 22. ). This has n@ connexion with the chondrocranial cartilage and has been named, the "Nasenfltigeln- knorpel", in the Characinidae, by Sagemehl ('85), who regarded it as the phylogenetic remnant of the nasal-flap cartilage of the Selachians. The anlage of the vomer (figs. 4,22) anpears as an unpaired dermal ossification ventral to the perichondrial ossi- fication on the inferior surface of the ethmoid cartilage. These two ossifications are distinct and have no connexion as dial the two types of ossification on the superior surface. There are no teeth on the vomer anlage which interdigitates posterior- ly with the anterior projections of the parasphenoid ossifica- tion by two pointed processes. This interdigitation takes place below the posterior margin of the ethmoid cartilage. The ethmoidal region of the developing Ganoids is, as far as is known, entirely cartilage at a stage comparable to the 32 mm stage of Amiurus. The only place where perichondrial ossification has appeared is around the ectethmoid process. The supraethmoid ossification is a distinctly dermal bone, comp- arable to the dermosupraethmoid of Amiurus, but has a transverse lateral-sensory canal ossification on its dorsai surface con- necting the supraorbital canals of the two sides. There is always a space usually filled with connective tissue between this ossification in the Ganoids and the underlying cartilage. The nasals of Amia are Yery much larger and flatter than the corresponding bone in Amiurus and lie on the ethmoid cartilage. These bones are developed in connexion with the latero-sensory canal system and enclose the anterior ends of the supraorbital are ¢ Oar. 4 >? A aM ‘oi! ; piuiashacs eid chialicec gobbled > edt date keteersuto os sed efit . -cfosbitesssll” edt ,benisn seed ssc baa rte Sebtdger ow ,(56') lismepee yd cebtateenadd om, tt | "Led ' i ae to egelitzs qalt-feera oft to vacomet olgenegotyd, SAT Bh ; Ns ge srscocre (85,5..eQtt) temov edd to @gnkme oat ~fevo Lalubaodottec edd of [axtusy coleeokttese Lamted | betis -omeli¢«reo blomive edt to eostine Jotrekah edd ao aba ES 62 molxegmon on eved bug fouttsih ets) Paotteeliseed owe a etedT .epetiue tolttecirs ode HO m0 teseitiseo to aeqyy ont ©. ek “toiteteog eevevintbtesa! detde.ezelans temov en} ao, diged on 4 hs a -boltieso bionerqesxec edd to enctiseleng to btedes emt atin BS seine goiteitgifretnt aid? .geescotg betntog owl ya) ie r ~ sepafiviso flomdts edt to otyraci yolsoeteog exit woled ond ee ,&i Shione: aciqofeveh edt io morget Inhlomite eff . er), oo eidetecwo» eats «2 tv essltiteas yvhetitoe ,awond, at 68 met feithaodslites ered w ovat fs vico ex? Cp tah to enats mi SE. bea e900 Ty Dicauivotoe eft hasots 6 Beteeqqs gad nortecrttage, | -—qneoc .enot Lamroh yitomiteth » st motteoktlaes btomdt estqse edt Setevedetd « sed trd .eoiwsimd to 5 Lond? eesqsre omae edt ot older “moc ecaluns Esotob att ae .moltzo! tiene fenao crevnes-Leredat yi etedT .eob! | ef? to elenen | vs 1 0 elexeo Latidroesqys. end gal oom meewied eveelt ovivevsnon Aviv belil? eliener ecace 8 eOgpiifene gutylted sy edv bane ebiens®) ed? wt noktsottises = i? cade setiel bus teytl dodm yrot 028, 08ek Ze alener amy ee 7) ° ‘peli¢tec blomivo ed? no eli bos eeuethmk wh eaod gnibacqnersoR - A -1O8Hen OTe? I eit? Atle fr£alxercnoo ai heqoleveb era senod , un ee h@zoeeqen oti to aban toltetns exté seoloue fae asteye. = a ee ee ox: 4.6 canals. The large nasals limit the supraethmoid, so that it remains as a small triangular ossification at the anterior tip of the cranium. The massive internasal septum of the adult Amia is comparable to the same element of the 32mm Amiurus. The prefrontal ossification (my ectethmoid) of Amia, is limited Seas | in the adult, to a small area around the dorso-lateral margin of the ectethmoid process; whether or not it develops perichond- rially is not known. The vomer in Amia is paired and toothed on its ventral surface, and limited, as in the vomer of Amiurus, to the medial part of the ventral surface of the cranium. As in Amiurus the palatine articular surface remains as cartilage. The ethmoidal region of the 32 mm Amiurus , in its cartilaginous parts is somewhat like that of a 25 mm Salmo, as described by Gaupp. There is the same massive cartilaginous internasal septum flanked by the nasal fossae, but the anterior end of the ethmoid cartilage is rounded off in Salmo and no ethmoid cornua are present. The postero-dorsal extent of the ectethmoid process is approximately the same in both cases, relative to the anterior end of the orbit, but the foramen orbito-nasale is much higher in the cranial wall and farther aeckeriee in Amiurus than in Salmo. The large tectum cranii is not present in Amiurus. The oblique eye muscles of Amiurus have no relation to the ventral surface of the ethmoid cartilage as in Salmo. Be- cause of the development of an interorbital septum, the trabecu- lar wall of the orbit has disappeared and the olfactory nerve crosses the orbit and penetrates the ectethmoid process to reach the olfactory organ. Gaupp ('06) probably selected the oA 3 “: -— Silken piat le . qht volxetis oat 32 soitsottteno idgieted Dade os: - \ ” ‘Ay wade tivbe eff To surtqee Sasenvednt eve * * mee ’ Thiet _ -epweiak mmSt sdt to dnoemeLe ome te qmoo ” nove betimtl ei ,atmA to (Bhtlerritesos wie | wr o ts ¥ b» : ~ sig ram fever ol- catch edd fnyors sets Cieme oot — . ahaGdoltee acéfeved it ton to wariedw nen ple -_ _ ‘ a be 7 — 7 » : beddoot fas Botiaq at simi of temov ent eirtaims $6 remov end at ee bet imtte bts z a tt Yo estetrse Lartnev’ ed? to teeg s@aeiigxas es ditares evshebe x2 igro tots enitefeq © salad Saimt . aivtirims mii S? edi To aolyet aoa or ao .C@ist mm GE s to ted ext l d esfwene at edtad FOR, $ eoontyefidgise eviccsm omne ont et oted? qore® fe tottedas oft dud ,seenct Laaan oilt yd Pamast? motqoa £ ‘om ban ones ai *to babagot 62 wpelatase bromukhe | ef- .m@agbaeto ent fe: 4 pt odd To Pitetxs [eetob-custeca ot nesetg oxn sorte: i {sober dtod al ease eit Ylotedixzotags St SROSOE: Hemeret eit tad ,tidto odd to. bae ah dieden ae itt fans " sotT evitiuy SeHD h) OnTg at try Ref . may P d fiw bed ; ’ eT ) . Bibs sot omdiwe a rd ito b. - y " 7 dh os -) otale £ eae exite 8 evrTsedo ond teadong eEELA fadw Bes gf onus, te j ; a Se : _: a Oe oe . “7 es Ut OSB C edt? * “ “e cd ytemteg beliso 4eF ! a oe 4 85 ‘okt . is att hes renod Lelot ‘tuetseqge taeTet _fstobtweqse : eat . ‘edt to ari ty he taeBeetcet funte say Te vis onw 9d ve seylte scet 8 <+ Clee, CF. a” rest eo e} ¢ - f fe | invests aes eden edt to boltaly = é mY O ‘ “. wine a porrenaey olitaler Tedto @ ay ihe wm Sem, aa viv sol xenure fad gel terso bronedgs wie wofed bas ow06 “AY B& BBSSOTS blom Wot 'trse off ve 49 considerably since the ten mm stage, but it has approximately the same topographical relation to the otic capsule and to the optic, trigeminal and facial nerves. The dorsal margins for the foramina of these nerves is as yet formed by the unossified cartilage. Below the ectethmoid process the cartilage of each wall fuses with the anterior end of the trabecula cranii of that side and, as in the younger stage, forms the posterior margin of the orbital foramen, separating it from the optic foramen (fig. 4. }. The posterior margin of the latter foramen has developed from the | ossification of the membrane which in the 10 mm larva extended from the alispheanoid cartilage to the trabecula. This ossifica- tion (fig.32.) is not a continuum, but is divided into a dorsal and ventral part. The dorsal part is continuous with the peri- chondrium of the alisphenoid cartilage as was the membrane of the | young animal, but the relations of the ventral part are not so es and will be taken up in the discussion of the trabecular region. This ossified wall is continued as far posteriorly as the trigeminal nerve (fig. 4. )and forms the anterior margin of its foramen; the dorsal margin has been described above as formed by the alisphenoid cartilage proper ( ). The posterior margin of this foramen, through which the main branches of the facial nerve also issue, is formed by a per ienonaxact ossifica- tion (fig. 4. ) between the ventral wall of the otic capsule and the posterior end of the trabeculae. The foramen for the passage of the ophthalmicus super- ficialis trigemini (fig. 4,oph.supzV.), which earlier was entire- ly of cartilage, has now ossified on its ventral external side, so that the nerve is enclosed in an osseous canal posterior to i Serta sece aN 7 » c @ 4 I 7” ‘i Ad , ai & “ ,olde® on} of Bae sioscno ofte. edt of & ob. fe. nie Z Baimerct ef) rot shiaven isetoh on? oom, FR, ban. fa -ogelltxrses Satticaokys adt Yd SomrotD sag ee we eeriet Sait gletaulxotds ead dt ted ceBees resi 2 ® » [ian depe to epolitise end Besooxg Bf omit ad 96 aiid Wofee any ih iS ebie vay to tinseto slocvedsat edit to Bane tol vet as od? seem 6 Jip a eft t0 aintam toliefeog eld smtTol ,saegve Tegeroe sd it BB, Be a cp) | 6ot. tt) ‘gomesc% pitqe ede mort ti wiltetages Meme tot feds | edz gout begoievsh sad menetot testa I Gat fo oi ween xottevte og Beficetace syiel om Of etd of cotter aaekeabel edz to aotfeo!: re -BOlTicesso gidt .Siiced=i1¢t adv ot eset ivasp blomssqetta a 10 + Eeeioh @ oni Bbebivid cf tid Mette. 4 Kos FO ef ($8. ia —treq. Git Aviv avyountinco ef Sisq ([eeres eT ttaq embing thom btoasdiqet fa odt 1° wnt? i i @ > > bol “ io ik Si i 5 le c i. Yi th] - , ae — ? ou Yorn 615 ft1sc Latitney adyY Sco teolitsiet ear gag keott e036 mir01 séfeosdezs ed? to molsuegesit. sii at as meted of fttw bas oth rte 4 68 witolhretsoq tai se Beuntines sit Slaw bet tieet afd® noes Sigzen icitevas ef? emrot Peel .» ett) epten a Be evods hediisesh xased vad ntateao Laerob eft seeeeet as actiefeoq oil . ) teu0%c epelidras Biko noigal ip edt yd eme to nedonstd abort elt Kolin donot .memetes sid? to tere | -S0itiveo feltbacdoliec so yd bewrot af eres! oele evred fetoe? LY ra eivsgee otto edt To Liaw letioey oft seowteg { |) seeS pee -selucedert od? to ime telvetsoq edt bos Wy : : ‘ “ft ; -teq suelmindgdgo oft Yo eyegeug etd Od cemeetod edt } : : » dot .| -VGgwe .fqo.s se BR) ialmog tse Bits ,eble Laminin: ce act © beltiesto won sad, well sis. J * 4 4 7 > of tOinetea< 7 miceneo de gl beseleme af evren 50 and above the optic foramen. The ophthalmicus superficialis facialis (fig. 4) issues through a foramen in the cartilage just above the opening of the osseous canal of the opthalmicus super- ficialis trigemini and innervates the lateral line canal organs of the anterior part of the supraorbital canal which lie in the frontal and nasal bones, (fig. 11). The roof of the cranium posterior to the internasal septum | is formed by the frontal ossifications (fig. 3) and the very thin | cartilaginous epiphysial bar. The latter is now relatively much farther posterior to the ethmoid region than it was previously and lies in about the same transverse plane as the optic foramina.| dorsally it is covered by the broad frontals, which are separated | from each other in the mid-dorsal line by a very narrow fontanelle] except in the region immediately above the epiphysial bar where These frontal ossifications are the largest they interdigitate. in the roof of the cranium at this stage and project laterally above the orbit in continuation with the dermoectethmoid (fig. 4). The ventral surface of the frontal sits on the dorsal surface of the alisphenoid and tegmen cranii cartilages (figs. 32, 39) and extends down the outside face of the former without being at all intimately connected with the perichondrium of the cartilage. Behind the eye each frontal is grooved for the reception of the suborbital lateral line canal and articulates with the posterior ossicle of the infraorbital series (fig. 3). The suborbital canal enters the frontal at this point and unites with the posterior end of the supraorbital canal to form a canal which extends posteriorly on to the dorsal surface of the (fig.1ll Sphenotic, this condition persists in the adult. The ossification OREN EO ibis tom, egelit+se eft of nemetet s taser “-xeuue erolnlzddco edd to: isase 2roseRe phn te: ! Aye re ; a. ah suegxe LIenss exii faistal ont actevuaitiiulan Nana mt shi Abidw Ceieo Ledkdroriqve edd Se tim toledne ant Aff .att) ,wemed feeen Sane Is ms : mngqes Teasmtetmi oft of tolretecq sdgake ef¢ Doiees eat ne i midd ytev edd Baw (E .y)t) enottsoitiage Ietnovt eigegerl Gop ylovidsalext woo 2! tettel sit .ed labagaiqtye etrormt levotvers eew si sadt gelygex pi omdde emt, 6b zotvetseq teil saulastot stige ait, se soate eno rope tt one edd/deede ab 1 Sevatsqee eta doidw ,eicstaott feprd eft ud Bevevas at th Aensinel Wertren YTev o Yd exit (aatob-Alm-edd at teddo a | eted’ tad Lsiegiqice eit evode qSet at beet nobnot end ane Veegtsl ed? ei enicitecitises jetroth~ensal .otadigihvedal: itt te mutes edt fo toon | aoliaynitaen gh didee edits eselwe iperoh odt mo eile [eivort eft 20 eosin Attala licato wepet be ftonedqaiis out % Baied Trodt!iw tem102 adt to sest ehisdee edd awoh shaetxe | r ef? to mpithnodeireq ef? ddiw bodsannos vletamitat mabiel a= Be 5 Bt Letnott dose eye edd BERGE 5 -omel. a - P Qn - Larose £ a Lag tai Che eri? to aes coi “0 ololeco sokretaog edtigt ‘i 1% .@t2) bic (G8 ,88 .egtt) nexelitzuse 7 - eeaJ isu baw gi j 4: sors etia 5 Te ‘ be a ' eiotae Lame od tredue i . Stans ond To bie col vere ey ait Ran ov vinelteteog Abia ‘x sf cveinteq Molt thnoo eft » it ieerve 6 mio! «o! Si.) oat pivaecliinese eT | lie ae Soe eons ga surrounding the supraorbital canal (fig.32.) is indistinguishably This canal runs fused with the membranous frontal ossification. anteriorly within the frontal to a point just posterior to the union of the supraethmoid and frontal, and from here passes into the connective tissue surounding the posterior end of the nasal bone and thence into the latter (fig. 11.). From the junction of the supraorbital and suborbutal canals, a tubule, enclosed in and osseous canal, runs obliquely posterior toward the middle line of the frontal and opens through a small pore on its dorsal surf- ace (fig. 3,110). Another dermal tubule leaves the frontal through a pore in its dorsal surface just posterior to the entrance of the supraorbital canal into the frontal from the nasal (fig.3, ton.) . The infraorbitalia (fig. 3.) are a series of slender, cyl- indrical, pipe-like bones, beneath and behind the eye, including within them the suborbital lateral line canal. They are six in number, each separated from its suecessor by the passage of a tubule from the enclosed canal to the external surface of the head, a so-called dermal tubule (fig.11.). The most anterior bone od this series connects with the ventro-lateral margin of the lacrimal bone into which the suborbital lateral line canal passes. These bones are typical of the teleosts. The anterior part of the alisphenoid cartilage, as we have noted, is unossified at this stage (figs.3,4,), and is probably converted into the orbitosphenoid bone of the adult which appears in this region (figs. 16,20). The perichondrial ossification between the optic and trigeminal foramina (fig. 4) o- pes a< fe. ‘ ie é eng: [Lense agdt nolisoleiudo Laraoet. | bed _ ‘ eds of tolwetsog tent, talog 2 oF Lot none ay middie Ofal soaseg eted mort bas ,fetnoxt das stmt ome 1°] feeen edt to hue voltetacg ant snibnvorse epsekd, svdé pe galtoast end. — -(.££ .92%) setdtsl edt ofat counts, at fesoloxe ,siudot s ,afanso letndicdse baw atterongae 6 ate Onl! eifbin ef? Srawol xoiszetsoq ylesptida euurt . Lago, “nee stume Leetoh eff so evoq Lisme 8 dgvotld Begs Are: fedsort | Bacotst Isicoxt ext eevacl aludct [antob. tedtonk. Berea a +), 202 30 eometéne efit et toliteteoq tant ecatupe Ieatbh) 828, al ¢ Leman eft oO1t {aductl ed? staid Sanne Lat idtos 5 q oe niyo ,iebeetie to eeites 5 onze [.E “Orn) atieticrendiel oat, Gat duc on! wy: Btreine Yrevie bitotes fentetalt odd onde yasuroy ) $i won ted | 89,3 S.8Ft) aisooedert ant ov senroant | eter a exstoo feseésev Boold stat . dottelet | a a ee fometd = fee ,semetot ofttqo aft ot toltetsty bee Levotar 8: ,oltd Thivedsoq edt tighews eretvae. muinsts edd SO daRG tb / if edit etetne Sivotes isavetxc si! .nemerek civxo oft 48 Z 4 -O¥itea isnisegit? eff to seusustd of0 Reewted enoted eb ni x (liVdo.r,& ig2t) evror Latout edt te sue teo ener est bionsigei te ouy to aigtem teitetsh¢ fsetob ade —s =tevecq shocettq fue ,elveqcso cite eit ot xo byetag dant ¢ bi -neiqes oft ao sotteotticeo fsanao yroenee-oretal ont chat iw -fenro @enee [stiso Bs etaveonunt et iiie's -isvebh btogediqeotiv1 ai} dsoda ysw Lexvéneg a at sate * Maested bax toute ,celvee etardetier efodw edd srotiguonts ¢ 4, TOistevne eff to nolttsottteso eff to ¢i{reer aie 2 ‘tt add of toltevns tedvie sd yom hme (few fatnero feperel. dad bexieq worl seelie cela tI .evrten otto add yd eters: “Seb ci vi .Setiecny ed yau +: tisbe eft ne saueddTo ,ere ee’ a. >. of eldatecmes | "Inoveotoe"me ca ome? xt stones oem we Be opie ticae to Pray Toltetms add ao) enimes ( Ls tc baonto frag arcet § , em@ee ent 10 tnowaofeveh eft ani ante oned mieato eft To" os eepied ed? af Beqofeved ef #1 tedd eyes (80) qaied | omtad at eegttus faxvtney_ oft bas eetcves Lat! row?nt etfs to dxsq 10k 18% + trevoetlo eft ,toneto? ,brre aolset nbdd %6 bins: vacate . ap eoglt .¢2dro odd u0!v9ete6e Srot tod #1 igcondt & aeiw emoeiteqsos ,wutwims ort vnsade. et idle dis . ml href — : =e ee ee - eee 53 the Salmonoid condition is not very easy and clear to the casual observer. But if we can conceive of the cranium of Amiurus being compressed instead of depressed, then the anterior ends of the alisphenoid cartilages where they unite with the ectethmoid process, would be pushed together, and the surface where they met would be comparable to the interorbital septum. At this Stage of Amiurus there is no ossification on the dorsal part of the anterior saa of the alisphenoid cartilage in the region of the anterior part of the optic foramen, although the perichondrium shows signs of the beginning of a perichondrial ossification both on the outer and inner surfaces which extends down to the trabecula. The first traces of the orbitospehnoid oceurs in the Salmon at the 35 mm stage. The alisphenoid of the Salmon is a later ossification, after the orbitosphenoid, whereas in Amiurus it is quite well developed before any great development of the orbitospehnoid. Speaking of the alisphenoid in Salmo, Gaupp ('06) says: " Entsteht sehr spdt ( Salmo fario von 40 mm) in Form von zwei perichondralen Knochenlamellen, einer inneren und einer Husseren, auf der knorpeligen Schddelseitenwand vor der Ohrkapsul. Im Anschluss an den perichondrale entstanden Abschnitt ossifi- ziert auch ein Teil der hdutig gebliebenen Seitenwand der Orbito- temporal region. Das Alisphenoid schliesst in selbstdndige Foramina den N.Trochlearis und den ersten Ast des Trigeminus ein und begrenzt von oben her das Opticum." The posterior alisphenoid ossification between the optic and trigeminal nerves of Amiurus , has most of these characters given by Gaupp for the alisphenoid of Salmo. He says little about the nature of the "Hautie" wall and its relation to the trabecula. As I interpret it, this wall is developed at a very early age from the perichondrium of the alisphenoid cartilage, since they are intimately connected in the 10 mm stage. The ES RR as SE ‘Levene edd of teefo bar yese prev tom eptuimA To mybnato ‘eid te evisenee £ ; woe to ebue totvetae eft nett ,Bee0ersh to inion Bromdtedes efit ddiw sittas yort oxedw itt eit to tig 202s moivgseiiiaao {[ebibsodeirod « to fatuaiset ertt to sogia € eis of mwob sictesxs raw Besetrirs aCe oi. Baa tetwo edt a ede wi euipso Hicudscactivdto gett to Ghost Jena ae -ogate ma G8 ent te. OO fiseltieso tet¢el 2x st nér{se edd to Siomedqalizs ed? ifew evicp si ti criuima oi coo ted ~pRonetesod tie edt 18 -bionteceotid eft ,mmiot emon a? ted? bar ,disnae nnoeveo fersdel ent Ee efavciwit efetnoert? en? mort ciotacse YLletitne ete eleise ~tehos edt ddiw eeut yort emrol to phitotsn ese af gad . ott tae, gid? Tro ta2ed esrtn EOLA to Jetvmon? of! -Latgeott tnebaece drt aatyl err eronetdmenm bexieo cs eteecre seueloe od? os dasmedatel aed nw c sa 4 i } ae fnges emii fayetal soci .celfeustoot apret Sat geeeeet. oF 8 ah ay Wino Gue sanrdwen eidy to ylinefinsqeiget vole aoltsoltiese’ — apy To eomebacqeint elit .ti dtiw Gavoonmes conconts yLtebaonem) sdf to aoitelet edd ml Llaw ylisleedde enone onal 20086 eibbia ert cewot yalbaetxo Leos teil yalbaperree sobvecitinns | -etauve San fetidtodue edt to aobtesw) eft godt Bead aff ss etttl Stnivel tery «l soltcacltipso Iaase etd ame j2isoso Sati i | ois ai0telus ol ogets elit JA tebe galylrebse oct Balbarowmge eit oo eanoitales apse ode Vileosiipsiq eved alata e) -oolasTo Jinbs of? of oved goede tout f fn) Mar i. 56 The infraorbital chain of bones whenever developed is related to the suborbital lateral line canal and in most cases the component bones of the chain are larger and flatter than in Amiurus, a condition usually correlated with the develepment of the eye. The anterior ends of the trabeculae are as yet continuous with the posterior end of the ethmoid plate, although the fenestra hypophyseos is more posterior than it was in the younger stage (fig. 3). They are no longer continuous bars from the ethmoid plate to the parachordal plate, but half way between these regions a part of each has been resorbed and parasphenoid and suprasphenoif ossifications have replaced it by growth dorsally into this region| forming the posterior margin of the optic foramen and part of the margin of the trigemino-facial foramen (fig. 4). The trabeculae of the two sides are connected across the anterior end of the fenestra hypophyseos by a perichondrial ossification separated by a wide svace from the more ventrally situated parasphenoid ossification (fig. 4). This ossification lies in the floor of the cranium between the optic foramina. Anterior to these foramina the trabeculae are united to the anterior ends of the alisphenoid cartilages to form the cranial wall between the orbital and optic foramina as in the 10 m stage. Toward the posterior end of the optic foramina, the perichondrial connexion between the trabeculae disappears, and osseous trabeculae, the anlage of the suprasphenoid bone extend dorsally from the parasphenoid ossification which now forms the medial cavum floor (fig.32). Farther posteriorly, the supra- sphenoid ossification extends above the ‘Bt halite ticickhiabeMoal ~ Geren inom ni bre Lance ark secede @ pisos at med} vedtell bar tes Sleydqoryi eds baited cof! detdw ,atéeenmet L[eead ont to, ¢teq oust eYSoeket oft fosted et ¢1 (50’ .qqnadss¥* sede”) momfne yitetteteny stom » of nobjomitatbextaoo af jepiretas ‘iso 19918 no WetAlq evontyALi¢rae oT =. ete eeriOt fehtedortaq SREEE 1 awo1rm ved a@rinimi Yo nolnest eft af roekt Letaae ee ene and is therefore comparable to the corresponding fenestra in is Salmo and mey be so designated. I1t evident therefore, that the connexion between trabeculae and parachordals has disappeared by resorption of cartilage. The dorsal ossification on the para- svhenoid, the suprasphenoig,has taken its place. In Gasterosteus (Swinnerton,'02) the trabecular cartilage has disappeared in this region as in Amiurus, but the floor of the cranium is formed by the parasphenoid except in the region of the | eye-muscle canal, here there is an ossification corresponding to the suprasphenoid of Amiurus. Unfortwmatelythe detail of the development of this region has not been described. The modifica- | tions of the basal part of the cranium in forms having an inter- orbital septum, where the parts are all compressed, are not easily homologized with the depressed condition of the same region} in Amiurus, and in making comparisons, this fact always has to be borne in mind. Also the absemce of an eye-muscle canal in Amiurus makes for differences in the development of the basal parts between the orbitd. In Salmo there is an elongate trabecula communis (Parker, "73: Winslow,'97; Gaupp, '06)) which is concave below and bears the membranous interorbital septum on its crested dorsal surface. I have found no mention of a perichondrial ossification around this trabecula communis such as is found at the anterior ends of the trabeculae in Amiurus between the orbits, and which is the anlage of the orbitosphenoid of the adult. The parasphenoid has the typical relation to the floor of the cranium that it usually has in the Ichthyovsida. MeMurrich ('84b) has described a basisphenoid in this ‘et bewagonsih eal PP bas =nunq edt £0 noiteen eee faexo’ a -eoa lp eds neket eat, wiawaiel Ogelivwsy tefuoedist off ASG" , 203s aca wh)? pee iz ‘to seof? ea dard permit atl ee wotger: eter al: Feat Ro motRe x sift wi tqeexs Sicasdeentag eae oo ‘Scbbacrnovtes sto) suosMiene we al anon exon i edd >. Lreteh sddelod saerenetnl rete pane Shel, hic ‘amelvibod eft .fudttoneb daéc For sas notgot Bt . ins SGetth G8 Salva acre: oy Drifesto ety De amg Suen sat 2 ° ag don ore ,focesiqmos ile; om -Ohcaq aAe eter e Sex smor edd jo noliihacg boeessyes spit dot Seed OY Bad @tewle font old ,equelageinss gatetom aut Bey &t Leake eloesm-sye m. to enoaeede edt cela babe 6 feaud ent to inanqoleyed eis at protewttts nets casi dro: walt Mo sexe?) elarwts clusedet? stagcole oe at ertadd, eesliaall a Qe@ed bra woled evsones at dotdw (180" sent aves, ; See @e8thte feexo) beveats att co mudqve Lad + {spodeauet ; ’ pi eee : adihal | Sadores aAcitacl inet Letrborodoiteq s- te sehen ae ‘bavot @ pe fo wwe sGiretTue aiid te beet ol ee dose Shaomeo eoeeeragas ie ie i en? of nodde bap .ntidxd est meewted exvesrieh al DOC ont bad Biohetvee@en oT .tinhs at! to Stein iteiainee edt to" ory Sileten fi Joasiy orotisto ett Yo toglt edéeeeeien eee etd’ «hl Alcuedeeterd a Lad i: one) rE F ( hoe}. 7 mene as —_ Soll aes, ead fe. ee’ 59 region of the adult Amiurus, as an "“indistinet ossification com- cletely fused with the parasphenoid”. I have remarked above, that there is an ossification on the dorsal surface of the para- sphenoid between the trabeculae and have named the suprasphenoid. In the piscine nomenclature commonly used at the present time, this is ossification is regarded as the basisphenoid, although it | has been known for a long time that it is not the homologue of the basisphenoid center of ossification of man, from which the terminology is derived. In all fishes where it appears as a distinct bone, it lies anterior to the hypophysis and is developed| from connective tissue rheaniaaniaee’ Cuvier called it the 'sphenoide | anterieur', but Hallmann ('37) pointed out that Cuvier's diagmosis| of this Rand as the homologue of the presphenoid region of man was incorrect. Concerming this bone, Hallman says: " Ein vorderer Keilbeinkdrner wHre wie bei die Stugethier-| en und wie als der Name sagt, vor dem hintern zu suchen. Aber mit Cuvier (der die Knochen Tig. 24 g and Fig. 25 us 26 beide vordern KeilbeinkdSrper nenmnt) einen auf den vordern Theil des Keilbeins oder auf die Mitte desselben sich herabsenkenden Knochen KeilbeinkUrper nennen, heisse aller Anhalaogie." Reasoning upon this basis and continuing to regard the hea behaneid as the homologue of Sie basisphenoid of mammalian cranium, he named the bone under question, the 'sphenoide sweeter! and maintained that it was found only in fishes and that it had varying developments in these. Huxley ('64) stwmdied the development of the parasphenoid in Esox and concluded that it was a dermal derivative and hence not the homologue of the basisphenoid ossification center of man, a purely cartilage development posterior to and below the hypophysis. He named Hallmann's 'sphenoide superior’, the ~ fj . wi } ; Pes grea, ; 7 —- - | ee ! «bionedcee shun ety Semen ‘ev¥ad ‘bets ce(ucodaat ent F ae te Beesteeinoameas ecud eLomenot ; i9f slavoddis .Stomecyetend off a= Sedceget ‘Gb tae | it don et ti tedt emit gamit s <0% a (waie Pmoue tg ast 20 sirmolono: dd dobre aoxrt ,xom tO ne ltasitiaao Se ts2ne0: Bi : iais co @ es Bteedqos *I areidie sefelt £la a .Reviaeb et % ci eve of fae ete estgoare vd? of “9 tvetate geal Oe st Mebiecelige'’ ads tt HoLLso ‘Telywd -smrcrem eomede tetesett a'xeivrd srdt toc PetAies (15!) anata Gee at Ban to ap iset Bblossiicee:1 sdi ovpedoniog’ ene 8a [2ye8 nealial ono sit! gabitreote> eidiesele afl ied tlw siks uetrt ted Lhel texebsey “Ota .2980;%) ve Sictitic cet tOy ,2hse ema ted ebied a »0 So .olt, bao as ake. Astoot eth 4 ob Ie! winhiovy aeh ton Beate (teten bey ie osx, Gelprustoccires Asis cetlegesh este ofS Bes ".elmoetin. telt® geeled (wansen seqeere O82 Bieget of paclicivunm ben ston etde ea | y i 7 ea —— Seiluciam to Dlvunasicbiaad eff To engofomod od? : %. ‘blo ; metteque efionedrs' edt ,sottveosc sehus onmed off Sena iat e a ie eT he ben 32 tadt box doit]? wi zloo Soookt sew €f gadé beatetshs 9 -Gaoft wt nduemefeved Biomedqvexeq wilt to teemofers) edt bol iete 128") wie . eofed baer evitevixed feared « vac ot sade Sohal oago ban 2 ,.,aem to tefneo hollooltiecso 6! omedqsteod afo Be bon olineni ody “oler bnu Of tolroteoy sanqoiewal pies 67 "so lSeque 5! orn: den’ gs ‘ reswent Lee one of 60 basisphenoid, but remarked that it was only comparable to the anterior part of the basisphenoid and that the rest of the bone persisted as cartilage. His reasons for regarding this bone as the homologue of the basisphenoid are, that in the foetal human skull the basisphenoid contributes nothing toward the posterior boundary of the pituitary fossa, which is formed by the long cartilaginous synchondrosis which connects the rudimantary basi- sphenoid with the basioccipital. Thus he regarded the bone as a rudimentary basisphenoid. Owen, following St.Hilaire, called it the entosphenal, and regarded the parasphenoid as divided into a presphenoid and basisphenoid part regardless of the work of Huxley. Allis ('97) re.garded it as the homologue of the pre- sphenoid bone of man and yet called it the basisphenoid. The development of this bone is the keystone in making the homologies and all who have studied its development have found that it develops from connective tissue membrane anterior to the hypophysis, and hence cannot be the homologue of the basisphenoid bone of man, a cartilage bone developed from the basis cranii. The cartilage which is enclosed within the para- Sphenoid and this ossification in Amiurus may be the homologue of the basisphenoid which never ossifies. This is an ossificatio peculiar to fishes and together with the parasphenoid it becomes gradually replaced in the higher vertebrates by the ossification of the basis cranii. Since it is neither the homologue of the basisphenoid nor of the presphenoid, it must be regarded as a distinct bone and hence the name proposed a priori by Hallman ('57), the suprasphenoid, may be applied to it, although it is to be understood that his criteria for distinguishing it are Pa. sf my rear " Rey, ie i Sey “_ eid of eldereqmoo yfno saw dt nae enod oft to fest ent add bas bionsiqek @8 ence shit gclbtege? 102 anoeset sit “Leet i fi | mempd fetect eft «! vady ,o7s biccetaptead edt W cdeseal i er it ‘gokteteod ots Srevot gabdton esdvdiveros bionecue ead a asi) | gaol ert vc heaxok af dotiw .ssaot (ist tadte eit? to sleud ered ies: wt ont geeenaee > ‘otiv gheotirodonye. owonta: 8 ee emod en! beSteasst ei esdt .tav lefoo obend edt dee Sto. befiso ,stislit.t& guivellot ene Sienetqubaed wrens OGnt bebivid ss bicneicebiay edt bebreget Sam Temedaeotae @ So Sror efi to sralixtaeget yaad bt ond gebead hus Brox | -et0 ori Oo 6 er fy sa ti be bia y. pt pre") eirch -blotwrigetcad eis Ti Beildo 38% Bec freani to ened ees an seo eaitan ai emorteyet eit ef agiod sidd te Supeao Lét08 ex? ever JnoemqofeveS adi felbictte ovad ofw Die baa se kan hemod, e ‘2 tolsevns ehetdmes ercsti evisceancs sext sqodeves ob tadt eng 10 suyolomon ert ed tonnes soned bre , edt sofort bagoleveh etted sualititan a ~em eaod. btonerigel P i2aclticso : t adc -volliseo tever dottw ‘Stoangiguiined od to i. « ; ti bi eit diiw +eddeno? bee sede tt ot relisoeg: | | eolzhoitiecs Welrsvy tesgia ont at Beopigest ei canbe ao \vten ef $2 oemt® bfmeve etasd ent: ‘Yo A te & Het o¢ Joum ¢1 ,Slomedvsesa off So con btenedaeten saa HemLiah 4 lxrolt¢ « heecaesy sown ett some Sap onod % sib tt darods 71 of belleae e¢ qem. ,btogedteszape ai ere ti gi) Aelovatiet) tot Stretieo Sin ade b Adonnsaer. MS mht Y ao. (ee 8 61 not used as the basis of the terminology, but rather its indepen-} dence as a connective tissue ossification above the parasphenoid and between the ventral ends of the alisphenoids. Schleip ('03) says that in Salmo the bone arises from a direct ossification of the membranous wall at the anterior end of the eye-muscle canal, and that it is indirectly connected to the parasphenoid and the alisphenoids by membrane which later ossifies. He recognizes it as part of the anlagen of the prim- ordial cranium which has no cartilage stage and says: " Das Bindegewebe, aus dessen Ossifikation sie vorgehen, geht in Teile des Knorpelschddel aufweist, und ist daher wohl nicht zu weit gegangen, wenn mam als einen Teil desselben, der nicht zur Verknorpelung kommt." Even assuming this view to be true the morphological relations of the bone must be considered before it can be called the basi- or presphenoid. The parasphenoid of Amiurus in its development, is like the large parasphenoid of the Urodeles which develops between the trabeculae and forms the floor of the cranium in this group. Its | lateral edges form the ventral margin of the lateral wall of the orbital region as in Amiurus. It is related to the orbitosphen- oid in the anterior region, just as the parasphenoid of Amiurus is related to the ossification around the anterior ends of the trabeculae. In the 10 mm stage of Amiurus, the place occupied by the parasphenoid of the 32 mm stage, is closed by a membrane which is separated from the trabeculae and already shows signs of extending above and below them. In Amia, the median floor of the cranium is continuous cartilage, a condition arising from - oe > § : ee yi Daetta ett reste: ted meine f : .) ai Btrocedqesreq sie eyode neltaolttean art ebboneéeetts eat to efine: | } 2 mort gesate encd ert omise ct stadt By bee ziteidas edit se [Lew sonardacm ofv to ms } Betoennoo yitoetriini si Ji tacit ome ‘sone oo “etel doid® eneardmon vc ebttmeétacife ext’ brs Bt -Gitaq edit tc neasias add to siaq 28 TE sesiagooes: ine ; | 28Yen Dos enare, egelipsusa. Of eat dolte sein | Mtetlentov ele i jéitiaad segaed ena . oferono hart eo" a na ffeen teieb tet bas .tctowtws Lebtdoslegtonx geo se teb .medfecesh [tel nents els mam Riew NOReROR. Ps ct -vemow br rey a oid Me pee baie | faotnofedaqiom ex? sxuxt ed. ot wel? gidt > a Le beifes 64 mac ii ovcted betes! BCS ed vada egod a to 7 blousdqnesa: 0 cee “ 1 exif el ,tnemqofeve® ati al erpek@ga Xo hiosedqesataq ont _ a «4 ee ea? seowiled eqoleveh dordw eelsbotld adit to i tonedqeateg bed ot S21 vacots etis ni meineto en: to 1o0lt.em senot Reult tS ti ei? to [fav Neretel of? Yo wbgram Lamhtew ont aro esgbe it. -wadagodidu « ‘ot ai tl .aemukes Oe os solper Sate exmpims to bloesdyeeteq ed? se tart ,codees to bsotas adit att a6? fo edu tolroson of! hues aolteolt hee) Seema belquo0e ¢e: a) ,somsrita to enute ame OF ody at _ 986s , @tesdmes a (oO Deuolo o! ,edete aq, Sh em0 Be btovedgemzag ee . bas eelvosdert eff Bae beverages: i : %e waolt malta ' ,ale al .ted? wosed Bas) } epode yal SO") Wiekie colsibaoe «2 ,spablénps sro: 18 % re 62 growth medially of the trabeculae and the whole hypophysial fenes- tra is closed except for a small fenestva just below the hypo- The parasphenoid physis which is closed by the parasphenoid. here has the same superficial extent on the ventral surface that it has in Amiurus, but its growth dorsally is restricted by the cartilaginous cranial base. The orbitosphenoids of Amia, one on either side of the cranium,are situated around the anterior mar- gin of the optic foramina, but do not have the same ventral ex- tent as in the ossification around the anterior ends of the trabeculae of Amiurus. The Parachordals. In the 10 mm larva of Amiurus, the parachordal plates posterior to the hynophysis, were rather widely separated from each other (fig. 2 ). Laterally they were continuous with the cartilage of the anterior end of the otic capsules, this cartilaginous connexion forming the posterior | margin of the trigemino-fecial foramen, ( fig. 2 ). In the 32 mm larva this is replaced by a thin lamella of perichondrial bone (fig. 4 ). It appears as if this condition arose from the earlier one by a growth of the otic capsule and the parachordal away from each other, without a corresponding growth of the immediate connecting region. Posterior to the hypophysis, the parachordals gradually j approach each other and the fenestra between them narrows to a mere slit as compared with the wide fenestra in this region of the younger cranium. The parasphenoid ossification forms the floor of this fenestra and a couple of processes from its dorsal sur- face project into the cavum cranii.(fig. 4, Ps.). With fusion of the parachordals with each other farther back, the parasphenoid Lg a ie hesablgatainrea o ‘Bogut ede’ woteu seit ddeusen’ Stank’ O% btochdqestsa ent . Bhonedqgata, edt yo Bp jota teid eostitwe fatinevy edt ado tietxe isla ne oul : rs ‘add yd Beteistosox al yllaatob dtwoty, otk god mew oe me end , alma to nBtowedqeaotideo od? . send fetas10 e 38 a | Tam Toliwetas cit hovore bovegtie ore ,weliere edt ‘wes ; ~ee Latdney ome eft ovad tom ob tnd setesret ottqo ait to > ed? Lo shae sagt .o28) 22 woted Bue a epelh . {Liew oft teutsage wida iirevisty eivosm. eds bas iquids ets setae, bu? vd BSearoo cew {ia sii to stenaity of ted? somebive antvis .culwuottte ett to déwow met go dukhavo ods te ro0olt bat wt efecet Llawe 3 ae omar ‘wat 960% Lebtosferteq due eliiggse otto evedt aolsoy oft MiPeRED Todt te . . bes eng? to ellemel midd [eexvob 8 dtlw beyeves Os srooex doot , = Beibsoocuzi .fecwl ati seores beetxe | VS .8) seis cedsty noqenmt: ei? Yo Ghuc tolieta» of) bae onvevnco sepeenet seeds “iso lreteog TOH oFeY BOnceceT coos .| YTS .gtt) modd atdtiw geeqgge Biageen tolvetua otf YC oeves coed evad tod ,egave tegnwog ene AR tare § .nolget etd? at ilvoocee od? te aoelt edt nis A, ite alt. per ; avb cow 32 ted? betets oe tnd ,enate om 8S edt at tobie?ecd yrov ecd¢ ts omlittsc edt ‘to vtseisejan i af enelitvteo Bevreado evad I .ow f = °® edt ¢a motteeltisae edd bus ouste ott el aureieoess tyanevet eft 46 wes PATEL neg fi¢ieo Innteire eff Yo aolssolt tena t effteo eff .onnl re ] vad tioutt om -bedtoaet need ‘gabe. a) i sai eliqaca add to seeseoota so hota ry 2 5 egives eli? Holds enete cm *@ef2 to tineex dolde a bucicovon edt of Latadlal-cetoh leds boumk ell) senenm eroatuefteteo Betteaq yd Of mort redone wn, ene) ai labrotoatan tTol%s taog mi? to oo hd abode ee de pa ott «teed od? to egelaw Lolrdbcodelted eft Mein sears ore 04 rs sot) Os «w Em@ Be teoexe eft Yo ten? Adie ~Lleotohsoretal 72. ged? towiwel down ylevitalex @ boteten a t feniqu ed? edtoqaua dobaw AE onay nae 4 | _itroa 69 cord and divides the sinus impar into the atria sinus imparis is more compressed than in the younger stage. It widens posteriorly in the region where the anterior processes of the scaphia fuse with the scaphia proper (fig. 2%), which are as yet of cartilage and articulate by rounded surfaces with the notochord. The claustra are better defined than in the younger stage; they lie between the scaphia ané the anterior end of the third neural arch, forming the wall of the vertebral canal in this region. The second post-vagal nerve issues poaterior to the scaphium (fig.35).| The most striking morphological feature of this region is the post erior growth of the parachordalia and the subsequent separation of the anterior processes of the scaphia from the notochord (fig.37). The enlcosure of the hypoglossus nerve within the eranium by ossification(fig. 23) is comparable with the history of the same nerve in Gasterosteous (Swinnerton,'02) and the first two po st-vagal nerves of Salmo (Harrison,'95; Willcox,'99). Schleip(03) has described the formation of the ossifica- tions around the parachordal cartilages and the ventral parts of the otic capsules in Salmo. He describes the basioccipital ossification as arising from paired inner and outer lamellae on the parachordals in the region of the fenestra basicranii poater- ius, into which the notochord projects. Anterior to the notochord the inner and outer lamellae meet across thia fenestra, but in the region of the notochordal tip they are separated from each other by an osseous mass around the notochordal sheath, which he calls the "ausfilllende Knockenmasse”. In Amiurus there is no fenestra around the anterior tip of the notochord and the e: ef atveqmt exote sixts edt con 3 Urerretaeq atebiw #3 omnte egy out a est aliqaes odd To aesneooty on egelitreo to fey es eve dofdw ,(08 .9tE Si | | eq? .Bsodooton edt Miw exoatiue bebauer 4d | etl wads seqsic teRrx0y odd ni. ondt- oecftar via Bfiors faxes huidd edt to en toirerus edt tae ue ei? .aciget sidd Si Tamed fe1det tay edt t AGE.att) mridqace ett of solteseang eoveat pia Beeor edf si xotnex afdt to. atatset imipldemell | géfieteres Mhenpeedve exit bre alishredoetag as | broteotven eit mo7t aiddac@ enti to nega . edd midtinv even snesolsocys eff? Yo te Wiotald ed? dtiw eidataqgoc at {8s ‘it )aoht aos, j edt bon (40' aot renniwi) excoteortaed ol alee! _xopkcta sce", sopiaral) on fee te nevtes | e@folTicso ei? to solteirot ed? Bbedixcossh ned (80) | Zo et foe tenkt botkier mort aclteita 68 “resHeq tiaatolsagd sttsenet et to aolges en? mh i wud ,agieene? «ht? ehotes feom eallomat sete bam * ce : icone wma : 662 a o ma @*tr Cent? gi? isbrcdooton edd te me y «ot dole ,dineh® Lnbacdocten ed? cai ee Cf a ) Loved! Oris ot ."eqemheclegel mM | ool bon fhrotooges ed? to abe i ed To 8 Py ts oe ten doctor ed of xottetar .etoslong Brodeotem oat : meres 8) a 70 ossification on: the inner perichondrium forms the walls of the cavum Sinus imparis. The outer lamella is unpaired and is thick- er in the middle line than on the sides, a contrast to the paired outer lamellae of Salmo. The paired rectus externus muscles are located in this region in Salmo. Further posterior in Salmo, the outer lamella has a spongy appearance, comparable to the adyeaydnad of the osseous lamella in the same region of Amiurus and which : Schleip says arises from the ossification of fibrous connective tissue in that immediate region in connexion with the perichond- rial ossification of the basal plate. From this comparison, I have condluded that the ossifications in this region are homolo- gous and that they are the anlagen of the basioccipital of Amiu- rus as of Salmo. The osseous lamella which I have described around the glossopharyngeal and vagus foramina and the ventral ends of the posterior semicircular canal and above the recessi sacculorum and cavum sinus imparis, have been described by Schleip and Gaupp as the anlagen of the exoccipitals. In Amiurus, the part above the sinus impar is preformed in membrane and only secondarily connects with the perichondrial ossification and hence cannot be exoccipital, though fused with it. The hypoglossus in both Salmo and Amiurus was not included within the cranium at an earlier stage, but is not enveloped in an osseous sheath between yenacneetl al plate and the occipital arch. The Otic Capsules. The cartilage enclosingeach membran- ous labyrinth has grown considerably since the 10 mm stage, but the relations of the septa semicireculares (fig. 7 ) have remained the same. The detailed description of these, given for the “| < eer te eo ee “ft ay % ? < edt 0 ef isn sade eae y | }- to tee ei Ses betteqa et alfems£ retwo odf * ft iieion Sit of tuextucs 2 ,eebte ed? xo sed’ Om — sbi oie od et 4q ue @ra eelsutrt esxaretx= curteet betiea eft prope B e632 .omis2 ti tottetseq sodiavi .omise ab) noiget wilt x ia ty x R oc etseage eos of sidatarmos, PRE SeIgS eaceg 2 5 sed. ' | Aotiw. bas avtistmA to noives enee ot mf el lomaLl ) woneee | evissenros anoidt= to ities cabanas edt mont seokrs aye | «Bioicivec oft Aviw aoltemios ai coige*x scsi bement | ‘tabi 9f F i patceqso: eidd wort .efetg Lacad git to =OQfeomod ets actnex sini nt enoks audtieeo end tadt sation ; “vir. Yo fatiobeootead e:it to seqaing.edt ets yond: sndlt, ; edd Baordcs Sedixvesed svar | deldw ol féues cwese90: 9a “3 egy to ebme [etinevy sil bas saineret arpav bose ise meroisdose beasoor edt evods dus Lanes coLusntoteay 2 ' @ause2 Bos alelidiot yo Bbeditoesh seed sved etis t a ¢ .etrage, soca mare, ta ,commbmsA Sl .elaticqtovere af? tH seein gilteinoces ylno Bns enstdmem ut bemsaterg ek soqat eunte o¢ Vonnes eoned bre noligoeltteso Isitbsodettsq ont aoe Rts evods ttagc sit GQ@iet djco «i etesecl(nocye st th ddlw beest darodé Hadigteoen telixee as ta suiinato of? obedte gow ton eew wm phssdcs oy Necwies sJaeds esoepso. Ge al beg fevne ton at tag -tores fatigbesd edd bas ad -sevdmen dusens*tcicae oyslitieo ext -aelveqad: ofto out tud .W7ate om i odd vonts yhdse tebiende anOTR oni. srarswiatiy pben!. ses over \ \‘ .alt) setelrotioigee siges eae fp, Lex | ett ef7 102 aevin oped? Yo aoldqiseass beLinges si. On edt , ae i Orr tae fa 7 _ A a) aoe | Ti younger stage, will also fit the 32 mm stage and the adult, ex- cept for a change in size. The parts which merit description at this 32 mm stage are the anlagen of the otic bones, whichin the teleosts include prootic, sphenotic,pterotic,epiotic, and opisth- otic. All except the latter are present in Amiurus, according to MeMurrich ('84), and the problem now in hand is to locate and describe: them in their earliest form. These bones were first grouped as the otica by Huxley ('64), who called attention to the fact that they were developed around the otic capsule, which, as cartilage, had an independent origin and only secondarily became connected with the parachordalia and the occipital arch. Hence these bones formed a natural group in comparison to the other bones of the cranium. Vrolik('73) objeeted to the grouping of these bones as otices, and, because of the relation of the occip- ital bones to the labyrinth, maintained that these also could be included with the otica. As Van Wijhe ('82),later pointed out, this was due to a misunderstanding of the original statement of Huxley, because it is a well-known fact that the membranous labyrinth invades other bones than those which are developed Vrolik also claimed that the otic bones took around the capsule. no part in the formation of the cranial wall because he found the opisthotic to be a variable bone, sometimes developed in the cart-| ilage of the capsule wall,againonot related to the cartilage, and We have no reason to believe that at sometimes entirely wanting. some stage in the phylogenetic history of the vertebrates there was another ossification forming the wall of the cranium in place of the otic capsules of today. Could we prove that the otic capsule superseded an osseous or cartilaginous brain case : at, 77 —"¥ | . r haa > -me .thrte ont fam enats. mm Sb ssid: : Ms noltqivoseh tivem dofaw etuaq ex?- eit mkefold« ssenod ofto odd Yo sensims. ; “eHtelqe Bre Oltotes , oitorete pphtonedqs: pee: “Ss eh a eS } paibtecos esstterbnh Si tnesetG exc t0tdeluend toeo fine efno0r ot ai bust at "Oa abidoxr oft Bos pret $@xht etew pened seedl m1 sesiitas wledt me eit ot wetiaetts felies ofw ,(28') vole ee antte e6t ee A Se ,fotd= ,efreges sito edt bavots beqeleved orem Youd ¢ emzeoed ylitabaoses yico Ine atgise taeboeee dat ae hed 0 sewek .note Ietlaiosos ead basa gi lnSeotoired eit oie matte efit ct cositagmoe of grots Jewsden s bemtot aged os To gatanorts edt of fotoatdo (8°) tbfor’s dnt num aie tae sGlooo efit To motdalst edt to oanebed. bag, otto as Rened ¢ 6d, bfveo Oefa sucrdt tadt ben taintast. .sitaiagdel edt chteoetill ¢ fco badntey tevel, °8') edfli sev Bay. @0Re eit ddtw 5 Ke Bo tnemetats [antnixo 8 te antinsatetreigugisns 1 Oe enh ee7. 6 7 e ¥ a 6 Mf eroaacdmen oft teriy toxt awemi-ileow ese ef #2 esss06d aX as, Siycs a beqoleveh eze dacifav eesti? and? nédod todge sehewnt 6 ik t v Se Lo abian S6et gencod solic ent tvadt Bemtalc cats #£foer o Larges ose te od? Dnicct ed eewcoed Ilaw intusts edt to moltemsoh ekg at ong 0 tiemee ,enod efdabxev a ob Oh) ettodtas i, eis ,egsittter ang ofl Detefou toncatton, Dew eluveqeo ede ‘to eset f= @add avnifed of coeas: ov ever © en baer prea ered? selerdedTay eff To yroveld 0! sesepolyig ond mb egete - ni @uiagero ele Yo Lhew ed? saloxed no ideodtiest wwdvous edd ‘ole svorq on BlveD .yabot te eelleageg tee eae sceo Gletéd cooplgsilvtas te suceeso as a, -$ie0 of? nt & c tr foe) Ate — a : a " - \siae no = = Saas. [eae ——= 72 wall, only then could we say that the otic bones were not parts of the brain case. The sphenotic is the most anterior dorsal of the otic bones and according to authors who have studied its development in the teleosts, it appears as an ossification around the dorsal anterior end of the cartilage of the anterior semicircular canal recess, and of a part of the posterior end of the alisphenoid cartilage. In the 30 mm Salmo, (Schleip;'03), the first sign of this ossification is an osseous lamella in the perichondrium of the postorbital process, and forms a ledge of bone which projects laterally above the hyomandibular articular surface and extends posteriorly along the roof of the anterior semicircular canal. The levator operculi muscle is attached to its outer pufitaeg, It spreads dorsally on the surface of the cartilage as far posterior- ly as the pterotic ossification which is developed on the roof of the lateral semicircular canal, and ventrally as far as the hyomandibula. At a later stage another perichondrial lamella is formed on the inner surface of the roof of the anterior semicircu- | lar canal. The formation of the adult bone takes place by the | resorption of the cartilage between thesetwo layers and by endo- chondrial ossification. Schleip makes no mention of the develop- ment of a latero=-semsory canal ossification in connexion with the outer lamella. A fine nerve issues through jthe cartilage and bone in this region to innervate the sense organ of the latero- semsory canal contained in the pterotic ossification. In the development of the sphenotic of Gasterosteus (Swinnerton;'02), the inner lamella and the cartilage disappear so that the wall if formed by the outer lamella alone. La 2 g » evkeq tol oxen evaed otto oft tart Y ol¢O eat to Iavxcb voltetns tecm oft et obtosetite 1 “s a tremaofevet ett Beibuve ever odw eroitan OF quite a feexbbh edz becets ccitaclPleso ae es etaeqgs SE) wevostet Re "Panst tefvoriolswe tolvet AB eit to opelittse edt to ctl 2 Bienedasife edt ic Same dgbnds sog emt ‘to ted 2 Mo Me agie géith oft ,(SO"gqtetsoc |, omLae sm oe eat at 4 OW So awivhrocoized ont nf allomal evesset ab ise vvenaane WD Sioetor foice eood to ogbel 's Barot, Sas) ppEpOae | Sitetes tne ecatist safe tive wa Led ebratto ced eh: erode ebse | .fenes thst ork iden so ltethe ad? to Toes edt sole Sl .eostrure tetco alt ot Bbefoslye si eésesrn Hsoweqo 0 Peterisieoq tat ta sgallixeo eft Ip eoriaas Ode ac Vilewron 4 m™ o Yoox ent mo Boqcleweb ef doidw ole porTgeee heute efit ge tet te ylistinevy bas’ Vakse 18 Luoptotags, Incwtnt' Si sflemal (etibaod ol requrpdy okies enzte tetist a J, et j tbs Pewotiotaea sotrevns eft To Toor eddy Ep portrite! seated edt 'a ; iy ed eoelfo sexed enod Pirbs end 6 <6 Lteoved eat » A & 7 . m | W6bme! Kd baa exeyal owt seed} neorted exetittie oii! tonmon | stoleveb edt to ncitmwem om eedem eto rdee coltsettinse ‘tats . dtivy colxennco wt sottsolt taso Lense yroeHon-soTetet a bo Lee but Opetlixeo oh cystidd sersst oyrten eit A Seen rota -orstel aft to any to oshee oat eterrerak oF BOtger alae vt -foltaulttiace otftotada als maf bonbat ace fenso. mwolcovemnef Yo olionedce edé to tiengetavan edgy al > ™ teocgenth enalleves ett Soe eflemal samt emt (20%; meires cf0is eiLoonl rebum edt ee beamed iow att we ere a Py NE * “ey on 73 In the 32 mm larva of Amiurus, ossification is far along, but I didinot find any ossifications in this region of the 20 mm larva. The ossification enclosing the supraorbital lateral line canal is intimately connected with the perichondrial ossification | on the outer surface of the cartilage forming the roof of the recess for the anterior semicircular canal (fig. 19). Just anterior to the cavum of the anterior semicircular canal, the ramus oticus of the «facial nerve ( the fine nerve of Salmo, Schleip,'03) issues through the cartilage (fig. 3) and divides into anterior and posterior branches; the posterior continues within the lateral osseous canal to innervate the next sense organ of the canal system. The perichondrial ossification and that of the lateral line canal cannot be distinguished from each other. Although there was no ossification in the 20 mm stage in this region, the anlage of the lateral line ossification was represented by a heavy tract of osteoblasts surrounding the membranous canal. With subsequent ossification the bone thus formed fused immediately with the underlying perichondrial ossi- fication of the alisphenoid cartilage and the otic capsule. The cavum of the anterior dorsal end of the skeletal anterior semi- circular canal is filled with osseous trabeculse extending betwee the osseous lamellae in the perichondrium of its walls (fig. 36). The outer lamella extends down on the side wall of the capsule as far as the hyomandibular articulation, but does not enter into the formation of the articular surface, which is as yet of carti- lage. The adductor hyomandibularis muscle and the levator oper- culi are attached to the outer lamella, the former having broader ny os ie 7 * ‘ al . - —y os an a A (a ae fies ius EE ae | pias mg 03 ‘edd to modpet sid’ nt Geiteet | | bhai ?4 shuts Boitecttiero fat brodotten edt ie bw etter i Ot tes . ‘ | exif Te toos od? pmioeet epebitzns ode So Seman : : oT : vest, . (QL .eth) Tengo: tetvoxletaiom, | ait ,luoke reli otto lmee: mieten ont 6: i S cellaading, jomtst. to evren eth ‘edt ) eveton fsb se oa o. eeblviti hus (8 mAltig)4 al eoned .oned Larogmamas is *biacteh erntalotiemen: tc ael Bae PT > te ovadloered edt ef doide 76 in man. It is also evident that all possible criteria should be utilized in settling these homologies, not alone those of adult relationships and articulations, but those of development as well. Ree e 66 @ @ 6 8 8 4 '@ @& The development of the mammalian squamosal shows it to be a@ membrane bone which overlies the otic capsule and is at first intimately connected with the incus (quadrate) by a dense and fibrous stroma. Hence it must be concluded that close association with the quadrate (incus) and the otic capsule is the primitive relation of the squamosal, and therefore, the most important eriterion in ascertaining its Peer re in the non-mammalian verte-| brates.” Comparing the above, with the statemwnts of-Allis, it is clear that the only bone in the fishes which: may be compared to the mammalian squamosal is that dermal ossification which overlies | the otic capsule above the lateral semicircular canal. The question of connexion with the underlying primary ossification is secondary, as is also that of the quadrate, for in the fishes the quadrate is separated from the cranium by the hyomandibular. The true squamosal weuld therfore, be the dermal ossification, de-| seribed by Allis as lying above the cartilage of the wall of the lateral semicircular canal; it has nothing to do with the arti- culation of the hyomandibular and is in the fishes connected | with the lateralline osseous canal. The primary ossification underlying it is the pterotic ossification of Parker ('73) and | is just as much a center of ossification of the otic capsule as are the other periotic ossification centers of the mammalian petrosal portion of the temporal bone, although no center has been found corresponding in position to the pterotic center of the otic capsule of the fishes. Schleip ('03) gives a detailed description of the ossific- ations in the region of the lateral semicircular canal wall in 3 « Salmo and follows Gaupp in his nomenclature, naming parts derived from membrane and the lateral line ossification, the dermosquamosa Hr te ed od tb ewode Lee sass ent a Zerxit ta al bos Crake. se + eollvet he bae éanch s yo (etesbawre) eront odd GFE Halottsicosse saofe tad aS ME 0 ed ts2m P '. @yitinizg edd oi elcecee-obfe ait bus part i ¢astrogm? teom off ,etoletes? has , Sae0meDp, Pe@iuey ceifamnan-aca este ti Yathomes ett aakate Bt $2 ShELA te ethwmetacn edd d2ie ,owods ed? gait | ot heteqmoo ed yamutotiw eedalt edt it ened sae P Petizevo fotdw nottgottteee camicated ted? al. Leoriniag® . edt. .fsaso reisos rotnee , Carer al. oly ‘etods | | | siliecitiess yieainge patyixebaa ods ath bw sed xen 0 eédeht ‘sci at tot ,steitbanp ext Re rads OGk2: et as ;? telod ERA ch ont yd mttingis a -sost podencyee ‘4 Leb pattenttieee (alereb ent ed exo Tinie itpew is eid 2o Lisw 6dt to easiitras add ovéda are v8 -té1e ef? Adiw ob o¢ antaton ced 2: phemes baw # | naneet oul to pein i H-olticeo ed? Yo doltatrossh helfaier es sovig (i (a0) ated abondon is ney tilteortoicse Inzedel ats: 4 ef an arindgo .evedeloreméa hii mt 4 . cewh edt ,90/tenthtieo eahk feveten an 77 parts, and those derived from perichondrial ossification the autosquamosal parts. His figures are clear and very easy to understand. The outer perichondrial lamella, for there are two, one on the outer perichondrium of the wall and one on the inner, is strongest where it is unprotected by the dermosquamosal. In the younger stages the dermosquamosal was separate from the auto- | squamosal, but gradually the parts become intimately fused. He cannot say which of the two ossifications appeared first. Toward | the posterior end of the roof of the lateral semicircular canal, the muscle fibres at the insertion of the levator operculi ossify and fuse with the perichondrial lamella. The articular surface for the hyomandibular ossifies later. In the 22 mm Amiurus, the two elements described by Schieip for Salmo, are present above the lateral semicircular canal. The dermal ossification contains the lateral line canal ossification and is partly fused with the perichondrial lamella (fig. 31). Toward the middle line of the cranium the inner end of the dermal ossification is separated from the cartilage of the otic capsule by fibrous connective tissue and connects by suture with another dermal ossification which forms the margin of the median posterior fontanelle (fig. 3). By fusion with the otic perichondrial ossification (fig. 31), the dermal ossification loses its identit as a descréte ossification, as does the squamosal element of man when it fuses with the underlying periotic ossifications. Despite the fact that it is not related to an auditory ossicle, I think that this dermal ossification overlying the roof is the homologue of the lateral semicircular canal of Amiurus of the mammalian squemosal. This homology however, 4 py es 1 sd ¢ reel tte Sx rg ox A aS hy : : a 7 ad ei temo Le besnodo bi a ove ae bid flaw ent to ee a Bet oetovranse si St vonttes:b eit ce dle ond vee pb 7m ween rd Owe Ong rag to me con B . ap eerte so, ex bat. +3 a Py ad os 7 evods tnoeetg ae Bets | A Gn exiae aries sotenett BBO oi? ddiw bout we me: 3 @ “ vineto ofit to vente otbhte ) ents woxt bed #1 Adee el a “Vas pth). . sit ite 1. eet f; norteok pea eae =i wt ‘a for ont: od kw out ab Pe vce too me . tt . Loar od ret st ta Si . T, . 78 does not apply to any other part of the comvound bone. The peri- chondrial ossifications are formed around a center of ossification| peculiar to fishes and called by Parker ('73), the pterotic ossif- ication. As in Salmo, the fibres at the dorsal end of the leva- tor operculi muscle have ossified and form 2 crest connected to the outer perichondrial lamella and extending posteriorly above the hyomandibular. At the posterior end of the roof of the lateral semicircular canal, the ventral arm of the post-temporal ossification projects in beneath this crest (fig. 3). The dorsal arm of the same ossification lies behind the crest of the eviotice ossification, above the perichondrial ossifieation on | the outer surface of the roof of the posterior semicircular canal. Posterior to the hyomandibular articular surface on the : dorso-lateral face of the lateral semicircular canal wall, the overcular-mandibular lateral line canal ends at this stage. The | lateral line canal in the sauamosal sends down a tubule which | opens immediately above the dorsal end of the operculer-mandibular| canal and eventually unites with it as in the adult (fig.11). | The canal vasses from the squamosal into the post-temporal, but before entering the latter the osseous canal enclosing the sensory} canal is independent (fig. 3). There is also a short interval between the end of this canal ossification and the post-temporal, where the canal lies unenclosed in connective tissue. In certain regions of the roof of the lateral semicircular| canal, the cartilage has been resorbed as the foramina left in the chondrocranial roof show (fig. 3), and the dermal ossification together with the lateral line ossification forms the rs at ef ast Ii oTeq 5 tO oat nat tris to tke nig Tac pares a sees wr Belt Lane odd ptoiie wiget snahirdad 79 protecting roof. The cavum of the inner ear and that of the lat- eral osseous canal are separated by the perichondrial ossification of the inner surface of the resorbed wall (fig. 31). Im the 60 mm stage, endochondrial ossification has appeared in some regions between inner and outer lamellae, so that the space form- erly occupied by cartilage is now filled with osseous trabeculae, just as in the more anterior sphenotic region (fig. 33). Toward the posterior end of the roof of the lateral semicircular canal, the perichondrial lamellae, both inner and outer are prsent in the 32 mm stage (fig. 31). The ossification of this region of Amiurus agrees with the descriptions of Schieip, Gaupp, Allis and others for the teleosts, but the name squamosal employed by them should not alone] A squamosal element is be used in naming this compound bone. prsent, but the name cannot be applied to the whole bone, as it consists of a pteroticossification with a squamosal element added (fig. 31), it is more like, but not completely in agreement with the mammelian temporal. The epiotic ossification (figs. 3,38), or the ossifica- , tion around the dorso-posterior wall of the posterior semicircula canal, has been described by various authors as a perichondrial ossification. In the teleosts it is connected to the post-temp- poral ossification of the shoulder girdle by a ligament which ossifies in connexion with the outer perichondrial lamellay In places the cartilage is resorbed and the lamellae form the wall, It is homologous with one of the centers of ossification of the periotic cartilage of man. This ossification is well developed in the 32 mm Amiurus ~ cw, — o ; | To taild ba te oak ee ‘i Bolteottings Lefthandctreu ait ye deter . edt ot .( 28 .aht) CLaw adress: eces at Bexrcseqcrs vsf goiveett tesb ee “greTt soaqe edi tent of .saLlenes totmo bas * seeisoedart ayocrec dtiw Bebfst won ab esses Suswof .(CS .alt!} nofget eitonedds TORE Sie cthotmes Letotal ¢dd to eqaneult ~ aah af Uneeta ste tetany bos samme tod: | esl foment, £4 LEO | (3 Lette 7 care Siiw ceetas enti Ty sotiet ed i Ie bein as odd Tot Srento bat tetas /wesae ateldee te. wot tt08 ; Yelcne Cebonesrdcet omee edit ‘tw6 (2 Bi taemete Lacometve A Seabd" Gatti ge ekrtt mnt oan 4 “ i > Si @ | Ls i i eee | arcois tau Birots merdct Cee | a @ prod elcotw eit oF be hig tae, ag t otttten oe bohhe tnemols Lasowance sg dditw Kobe It iewop tt orate @ oJiw taeteetan ct ylefefdmodston See emEs srom st @2 ° ; -terogne? mettnm ssotticeo ot to ,. 68,8 .6utt) coftacltieas 912 ake que ‘ha r Sivoticines toised it 36 Ifey To) 102 a6q-C6Tb, Miah , Prhntod ol ts¢ 6e eLotive asoiiay yg dod ir saeh sna . ~' '20d On? oF Sbedvosantoe ef tt eleoebar ote La ngs Pt | jos iMereyil s vd olfeths -tebilscte ead ee aN PC. 4 emi Léelvidosdtoimeq eaggo edd ; ae Ate oor ne . Re <1 Ree ee pe ofl qd? 4 Sklic oft bne hedroret cS piece ost ‘ r% , ( ° i> Ff aT neo ed? ta" : : y, | 10g ; . treq. ' , | ( - Rap © / O69 Al Beqeleveb'. Piow eh, an * 80 Inner end outer osseous lamellae appear in the perichondrium of the dorso-lateral amd vosterior walls of the posterior semicireu- ler canal. The ligament which connects the outer lamella to the post-temporal is just beginning to ossify (fig. 38). he poster- | ior dorsal part of the cavum for the posterior semicircular canal is filled with osseous trabeculae continuous with the inner | lamella. Ther is no resorption of cartilage at this stage. At the 60 mm stage, the perichondrial lamellae are much thicker and cover more surface. The outer lamella has extended ventrally on the wall of the semicircular canal so that it meets the ascending exoccipital ossification. Near the anterior end of the posterior semicircular canal roof, the cartilage: has disappeared and the outer lamella alone forms the wall. f The occipital region. This part of the cranium has grown considerably since the condition described for the 10 mm larva. The cartilage forming the posterior margin of the posterior fontanelle has grown forward and together with the medial edges of the otic capsules forms the synotic tectum (fig. 3). There are ossifications on both the inner and outer verichondria of this tectum, which have been described in other teleosts as the anlage of the supraoccipital bone. The morphology of this bone will be discussed under the adult description. Sagemehl ('91) claims that the supraoccipital of the adult is a new formation in the teleosts and is not found in the ganoids nor in the dipnoi,| and that it is the result of a fusion of one or more vertebra with the protometameric cranium. te Retucalea ee sess ~~ on Sustiotmer torrsteot ef¢ to elfen rolreh oe re at GY silemet zero edt eheeitos dohiwy Ee avetece eff .f88 .aft) Yhtsbo Wt au beigee, fen abt tafvetictroe Tolvetede edt tot mippie ae pale sia Pteant ed? Adie coornitnoo-sAbvosdon ayORERe ae 4 oe eas -eaaie cidt to enetitiss Jo noliengeet on ok eed elle dome 4t2 exifenc! [otvhinotioizeq edt legeoe a 08> é bebacize sac cliews! tetfvo eAt Look hie Yom. tered | . = 7 $i dais og fanso teivothetdea edd te finw cdma Le ‘toftetne ef¢ faci .noiiaelifeco ieladtubstcssior= onefitites oct (toot Inaro we lvombokges elaine few of} omrot erole alfemel setys’ av eam fem a ) ier ani moineto ef? to Twsg Shit Jevtel om Of ost tot beditoageh nottiians eae eonke Sie or 6 a a ee one : - . ; } ; eae) : 7 ae tolvefsor edt to eles t6olrsetS ent , a Y TA = & atv ad e og gaimnrot iad = = rn +. oe % wire Senboe [athem sci citiw asi eqot Pits reawrot avery end - wed, i” wt Voge cent «\ .ait) mrtcet olvonge eid penta velLyegne | ot 36 Sizbrvdceites teatro ‘ina tenoi ear | ited iro eAgv ce ataools! rtedto at fedivoueh oced eva fhe @god “ldt “o eeoloforom adTl .ened fad iehonenagy oad v0 | ff’) {tenessc .tottatusaeh dinba ed web bouawoets of iw gsoltrertot wen i tisbs éd%. to Lot le teoemtenne elt tedt p2eacth ear al ® adil ed al bowot ter ei bie etwosted 0 me emdetrey 62° 6 oto to coset & te acu as et or oe - @ ap r «ai f . . Yee ky i) + PEEL tO of wandenotory it ddd vr ‘Vea >. Redd a ale @ . -_ = . 81 In Salmo (Schleip), paired parietalia are present and form descrete bones in the adult. In the larva they develop as dermal sheets dorsal to the otic capsules, fused anteriorly to the frontals, laterally to the squamosal element of the squamoso-pter-} otic, and medianly to the anterior ends of the supraoccipital. They are separated from the cartilage of the otic capsule by fibrous connective tissue. In Amiurus there are a pair of such dermal ossifications in the same region and having the same histological relations. These ossifications are fused medianly with the perichondrial ossification on the margin of the posterior fontanelle (fig.34 ).| Despite this fusion with the perichondrial ossification, these | dermal ossifications are comparable to the anlagen of the pariet- alia in the developing Salmo. The adult cranium shows that these ossifications do not persist as descrete bones as they do in Salmo and other teleosts. lLaterally they are connected with the squamosal by a thin stroma of fibrous connective cells (fig. 31 ) and anteriorly are continuous with the frontalia (fig 3 )} They have no lateral line relationships. The details of the developing supraoccipital ossification | have been deswribed by Schleip for the Salmon. The main part of this ossification, according to this author, develops as inner and outer lamellae in the perichondrium of the synotic tectum. The median dorsal fibrous septum between the dorso-later al muscles of the two sides of the body ossifies as a vertical osseous plate above the outer lamella and connected with it. It supports at its dorsal end a horizontal osseous sheet developed from the fibrous connective tissue between the muscles and the Pry yest ‘eyes? at Zz yprerbe aa ot Ulxelmecne hoawt ,zakoegar otto oat ot iE q-csomagpe edt to tacmele Lapomanpa edd ot} oes? “ovteeonnge PH © emeivecitieco Lamzeb dove to theq 8 ots ered? anna sth. i. " Jenettele:t Cfaotanoloteld emas on7 yelved, fas notger ene “s fatcvbnodoited edt ditw gloavddom beet mth ssc! tosttteee @ Bt pS sit) oLlenatnct totretuog edt to odadass edd Bs) aoktao Mm fest ,soitaciticac ~bnofelreg pitt tthe soleat ett ot pa Latetreg eid to mepelue oft of 6lde “eqmee oie ecoidsert ieee J | @ebed? tedt swode mwinero tiche od? 6 .omige gaiteeferes sae ae ot Py: yodt an vendd ete 10ush as terete ton ob Jat ot ed? dtim Bevosadoo cx yode Uhtessthl lelpeeepee aedse as fh .mtt) affeo evitsencor guotdit Yo amovterahe SS %e it & wit) si lector add Atif ev sats 3 a yiltatvrodaa fue 3 ire -koidesotvslet 6ntl Lesegke on ered Boigacilisso (etintlosesravs yatcoleveD ety Te eltaved ed? iy an tieg atem el .momizh ady rot gisises wa hodiraeeb heed | | - ecoleveb ,rolcve «Ley of aatbrbedcs £0 bial thee n't Cligomge ods to malthetonotteq edd ot ext Lembs tetwo Sua cs ‘vehi H \- ' f~fetoh eff mhewled matase syeoyvdts (eetob’ tikBiam ost mt ood” | trottsor 0 odap tice bed ett to: Coble Gian ian ¢ ott dtiw hefoenios face alklemefl tetee ott evode stely 0 | , | paclevel Jeeit tipesno Latntndcod ie) Bee Lattoh a2 t eond to one | odd O08 6éfret io neowted empal) ovivoonags peut wt Pe . - - id A aT ae eT — — - — 4 be: * we oat uf a ce ; } ¥. 82 corium. He calls it the spina occipitis. Both inner and outer osseous lamellae extend forward on the margins of the fontanelle anterior to the synotic tectum and are connected with each other by a transverse fibrous sheet which later ossifies and forms the roof of the cranium in this region. Schleip maintains that this fibrous sheet was originally part of the chondrocranium whose ontogenetical history has become shortened. In Amiurus at the 32 mm stage, the synotic tectum, as remarked above, is well develoved. Inner and outer osseous lamellae are present in its perichondrium (fig. 34). The ramus lateralis accessorius facialis and the jugular vein of each side are enclosed in a canal formed by this perichondrial ere along the posterior margin of the fontanelle. This canal has | its anterior end at that point, where the nerve and vein extend dorsally from the brain, medial to tha anterior end of the post- erior semicircular canal. In the 10 m larva, this nerve and vein} lie dorsal to the cartilage of the roof of the posterior semicire-| ular canal. Since that stage, the cartilage below the nerve and vein has been resorbed and the perichondrial osseous lamella forms the floor of the canal in which they lie in the 352 mm stage.| The outer perichondrial ossification together with the parietal 7 ossification forms the roof of the canal, while the cartilage of the synotic tectum forms its lateral walls. Near the enterior end of the otic capsules, the peri- chondrial lamellae on the margins of the fontanelle interdigitate with the frontalia (fig. 3). There is no lateral line ossifica- tion anywhere near the vicinity of the developing: Supraoccipital. a. (RD ay Wi werd. t redo fue waht 8908 .eltigtoco sedge amie a SRD efleaadne® edt to attigian edt 10 eo hiteite onl! Teddo dose avlw hevooanco ofS Hna movsad oneal ait ea? ea@rot fas teitiaso zr9essf doidw togte wee he eted tod? acietct an cioldsd .sotnert elit al aubiails' a esodw mrineatoorineise sd¥ fo tisq wlienigiae aaw sat bemsixods smoped) Bad qrotetd £ 7 ee .uirios? citonyws en? ,dasts om G8 eid ge owtckah a vy efessoc tétto bee teanIl «.becoteveb Eiew ef evods : eumss ect .(28 .git) oytr Anos of t6q eth nt daeneng ote | ebie dose to siav telesaecl era iri pilstosl asfterseenos Gotiaetifiess [a«ixrindtisiitse elit wa baa O27 less & pt hose ; ne 6 set faeen eid’ eLienwiro' itv to ‘te 62 boa epee a efoatie ota steel .(Qhuafih eRoLit ts: | alt) holgeolt ieee slat te. bows vituetinedehal new bts Bed doxsiw ol indy esi Qe bed nade: ed fenso eat ne Lircut lata ogeeney | intbom ond a0 evoowg, 8 mb (elt$aodorreq eats mm 08! 4 (1) bra @pelies edt to com nit) ytted tehermeb end 2 leergs of! exedw bedvouex aed eed wat edt ¢ besi#t ¢tlivvenr Gavotte ore saeetnndives l-otgow odt ot ethiw aay xo Buena iF 4 or 1 # “ 86 in the ganoids. He says ('82) that this bone is distinct in Polypterus and Amia and that it is fused with the dentary in Lepidosteous. The dentary is prsent as a dermal bone ohlhy,in all of these forms. In Salmo (Schleip '03) the dentary is made up of the same elements that composesit in Amiurus. McMurrich ('84) recognized the elements which make up this bone in Amiurus. The posterior end of Meckel's cartilage is covered by a perichondrial ossification, the anlage of the articulare which furnishes the surface for articulation with the quadrate. There is no independent ossification on the top of the coronoid process corresponding to the autocoronoid of the ganoids (Van Wijhe,'82). is represented by a small The angulare or possibly the goniale the The lateral articulare. dermal ossified sheet ventral to line canal leaves the dentary at its posterior end and extends ventral to the articulare and thence into the preopercular. In the ganoids the articulare is formed in the same manner as in Amiurus and has been called the autarticulare (Van Wijhe, but has a dermarticulare attached to it as an independent bone. In Salmo (Gaupp, '06) the articulare is developed from two such elements, the latter containing the lateral line canal. III. The Adult Skull... MeMmrrich ('84) has described the cranium of the adult Amiurus catus, but his description and figures are very incompletgq and could not be used to supplement the points brought out in the} first part of this paper. Other authors have made passing refer-| ence to the cranium of the Siluroids in general, but none of them give a specific description of the osteology of any one * ak toatindo whence push dase sl etstnes: ed? dtLer beext ol tt fed oe mi. vide exod famx at otek nous Alias p —_ eia0° ,O00IW meV) otelentiretu@ sit-folieo mae end bag e000 thehaogr bat sm os $2 ot baossae culoot sane dire owt mort beqolevod 61 etukdokdae ent (aa? 99789), 08 -ifitac ontt Iscevel ett anintadnoo ret tal on? , hae ss +ishA edt (2rr | | i) to moiaerc o> hedixvogsh aul (2g?) eee” oinuceal x: O78 Bertsglt bye golivizoash ei aae agtse : fe ni thane: taloqg edd treméledge ce Seaw ee ‘Jon Bcooe i ~“setet salessq efam eval gtotige tedt0 ae nee dxsq ort | % i oud \leveneg «) ebtomcie ene Le mr ntes 6 odd of one by ‘ 20% Yacloetao ead? Yo coldgivsgeb, tine but me i 87 species from the point of view adopted in this paper. Pollard ('95) gives several figures of the chondrocrania of some of the South American forms, with a brief general description of each, Herrick ('01) but no reference is made to their osteology. remarks the topographical relations of the cranial bones of Amiurus melas in his discussion of the cranial nerves... The cranium of the adult Amiurus nebulosus (catus) is more depressed and flattened than in the later larval stages. The ossifications laid down in the 32 mm stage have invaded and There is however, more replaced the cartilage in many parts. cartilage remaining in the adult cranium than MeMurrich ('84) noted (ps271), “very little cartilage remaingninithe skull, ‘ithe anterior portion of the ethmoidal cartilage alone remaining unoss- fied". I find considerable cartilage present in the floor of the | cranium posterior to the ethmoid region, between the otic capsules), (fig. 7 ) and in the semicircular canal walls. The posterior instead of the anterior part of the ethmoid region remains unoss- ified as the internasal septum, and will be discussed with the supraethmoid bone. The fontanélles of the roof are well described by McMur- rich (p.270). My description of them will be more complete, as I have traced their formation from the younger stages and have followed the changes which have resulted in their restriction to The ossification which divides the median region of the roof. them into anterior and posterior fontanelles (fig. 10 ), is formed around the epiphysial bar of the larval chondrocraniun. Most of the bones of the dorsal surface of the cranium have a delicate sculpturing. | hee a», - Beaffel .1egag inv at Hegqeis welv ‘ eit to emce To rine tsorbacdto edt ‘to 36 gaose Te noliqizousd ‘Laxened Teizd a ddiw , aie (f0") #oeiuteHd .ypolosteao tiedt of Sham ef ecco’ “eo 4,7 to eexod Isicety oft to smo?ialet Ieeidgergogot by ol: sevien iaineato eit fo AC Le emeeED edd at ceten oo at (‘egteo) aveoctInden songimé Jiubs edt to MHL ORO ont? . ° oe Boga favral tovel ent cst reit berettelt Snes wth eae bas. whsyn! sved egeda mm SO edd mk coh DBE no tnorttese ter “ta exdu ,tevevot si exeil .streq yYaem at @pelepras oie Beos {ey BAS ec (36") solcroMol mad? ciimervo tisbe ede’ me Sahabedes sent 8 ar 6d22 (fimdadensinkigaisme: epatlineo.eftdit sah? «ath Sa0ay gulnlsmet encls onsiittso Lahtomite eld TO iat ; “at f ree A: Pres: 4 ; Medd to t6e0L2 edt at tneserg enal Lived eldwabblamoo ‘het? a ? i. . eivcass 0 Ido est asevied colnet hihotite’ amt ot rotredeoq ow Inst, Le P a Zofivsiecoa eft .elisw Lanree “eliuottotines git bas aston : ot eBe0n: enis vex otnes Btopdtea ent 26° Pegg totais eit to beetom edo ddlw boraucath ed £Lin bre antjee Ceeamneted suit as bet ood ptomtt ee nga ~fimok YO HDeditosed [lew Toot end? to seli¢nadae#r edt vi ée ,otelimoc siom ed [flw medd to noligivomeb Wt ZeORiee) sols | 7 . S'f80 dite teznic teanvoy edd mort wot ‘tam ot “‘thed? Boor? eved a ncitcolviaer tiedd ao! bediveos eved doldw sepemio ene bows tet 4 vib Moldw@ncldsoltineo edt Mode sit 1) moige as item ott -a'1) selleaeteot tobreteod Bak Softetns Otne” i | Ootireno Lav! dt to ted? Cetogdetas’ olt barony Be ia u % Lo soetive Leateh edt 3O Be nod edt $6) eo ‘oath bee 88 The Supraethmoid (figs. 6,7,10). This bone has been des- cribed for Amiurus by MceMurrich ('84), as the mesethmoid. This name implies that the bone is developed within the ethmoid carti- lage and not around it, as has been showh for the larval stages. In development, the bone arises from dermal and perichondrial ossifications. Allis ('10) has described the bone in this region | of the mail-cheeked fishes as the supraethmoid; Sagemehl ('84), a | dermal bone in this region of Amia as the ethmoid; Parker('73) and Gaupp ('06) as the supraethmoidale, in Salmo; and Gegenbaur ('78), as the ethmoidale medium,in Alepocephalus. These various terms have been used to a greater or less extent by other investi-| gators, without regard to the significance of the terminology used. I have used the sccusseumes of Parker and Gaupp as it applies better to the bone in Amiurus, than any of the other terms. Very few of the authors describing the morphological relations of the bone, have studied its development and earlier histological relations. Those whoc have done this agree that, | in most teleosts, this bone has two parts, dermal and perichond- rial, respectively. In the ganoids, as represented by Amia (Sagemehl,'84), the dermal element alone is present in the same position as that element in the teleosts. A comparison of amiurus| and Amia will be made further along, after this bone in the former] animal has been discussed. In some of the teleosts, the seulptur-| ing on the dorsal surface of this bone is very rugose and it isc covered with numerous spines. It is usually an unpaired bone, ital diverging posterior edges interdigitating with the frontals. In Amiurus, the supraethmoid is the terminal bone on the dorsal surface of the cranium (fig.10, Be)... Its dorsal oes ee hy aoe ee ar : as. ; j : hy i | ay “Sef used ced exes etd? (02,95 .eatt ) Be etdT .bhomitesem of? ae ,(28") dotrsftelt ¥ o stites’ biomite oft ciitiw bauettees et ante ont seesete Lavtei ed? 10% dwore meed cad as tt Sapvots eo . a LaixSoodotteq baa Capizah moxt eeatxea enod ent tremgorey “8 Sotget elit at encod edd Sed teeeeh cad (OB) SeELA -ssoldsott tes e .(328') Gierenst ;bicmdteervqee eft es seiett veieedo-£tem pei: (EV' )reata ;Siomive env es sims to Bolger etal: at enod pa pry peivGevei secio yd cuedxe ucel To tetsety. 6 oe be esr seed oved waofonimzes sd to eomsottingés eid st Ss ‘TSRet twonehw . : oi es qgra) bie rextel te Eicivindatet ed? hees wid ; ry tedgo ero to yoe asd? ,srimigs AL enod, and of nodded bate ~ »* sciyoLodqtom edt saidivosst areddss edd Se wet vxe¥ 7 seifise baa tnemgoisvel avi beiboteretal’ en60 eit to cae edt setga eldd each eval audt seuodT -swolvalen faetgotots -factioitec Bue [amteh .,ctteaq owt ered ened ait? stwoelet eon | | fi | alm jecetqet es ,ehlionssg acid ir] ovsteogwet att emep edd ol ineeetq si enole ¢nemels fantwb edi (ee! "doweaaell 7 Siwvirs to mositaqaco A .etecefet ont at tnemeloe Gade ee oon ty 0085 ef Holtw ,soature Tasted ett rs me ¢ ony ewe at | .a.dte)sdoton 2 To rigran ‘ond riot planice ‘botite oven sict of frersge2d .enod ext? to an ae Holdy .esureo owt vat ebsee ened et ,emiirae nt 2, ‘Ro Biveet ef! ers Sn: «tits ets ‘Te seahe Cetoret-xetas Siow? enoitasitieac famied fettuey 08 canes to vireretas f “Rigo sd? .ogsic dotdw ta ,svgél om 85 eit to smaxes senate eat mi dofevss 2 aised yedt dgadkid fs ,theséier den ee 4 Sf? gitmoxot ,vitolretms tedtto ose eres ent vedt prion eff Yo [few xcitetne od? fas mortatyo of) Te atytes solvetne ¢ Me biewoe Bhrotxs dotiw esoagt #\egofome PodT), Re ‘eco | { V.eit},enod jas So tia Loivrbixod ¢ troq: elt, as tet ao igi . | sostius Lortrey oft fo ylvotracdot ebpotke feeds it sf Beeies siT .(df.5 .nalt¥ dodetalt trate urer. is celeb sit 2 ° ~Lizeretc serif to fevotat yd yids heed a0 ae Daa siinpidiane’ evstt:7e [ertaey ati ot batodétitco Vhenwto ete dekaw } F On? <9 mistes tolistas ent § .ei nn av Ovens sit egoxeas tte | Bot ,nolvuclilesc L[etiney ef} pie esthedponeanalt {.0e¥) ; Tegit) blonds sid mort nalpotca Lavevee’ 2 ro Lavomet 0¢ tt sttw toataco af) oie cots ats |, ( ‘i -lgtho Io esetive Deord 2 of Lemtcey sefl SRCRRaREee ed? | vipa’ ety To ToC ine. «olteteog ent swear dot sin one 1 ot elt votd? aottsen Lantbittandl a 6 «uniqes I 7 s(t ed enotvagitieno eds to erakeeiee ‘eae rv s rt) J zg i ml dotdw dortsoftises od? -ta8" tgnord \ELom - a feiclisecue off Aviw se ad sl toyel Setrhnodet eg - _ ee — ee 90 ossification, has now penetrated the cartilage, which in the adult is entirely ossified in the anterior region. A transverse section} through this region of the 60 mm stage shows the beginning of the invasion of the cartilage by the bone, both dorsally and ventrally (fig. ). The posterior margin of the internasal septum persists} as cartilage (fig. 7 ). It extends dorsally on the ventral sur-| face of the dermal ossification as far as the interdigitation of : this with the frontals. Ventrally it extends as the floor of the cavum cranii as far posteriorly as the enwevdepnendin (OS.). This disproves McMurrich's statement that the anterior end of the eth- moid plate of the larva remains unossified in the adult. Anterior to the olfactory foramen, the supraethmoid and the eetethmoids of each side interdigitate in the wall of the nasal fossa. Comparison with the condition of this region in the 32 mm larva (fig.3 ), shows that the ossification of the supraethmoid and the ectethmoid is caciancnesaey: and is developed on the outer| wall of the massive internasal septum. The jagged suture between | the two bones extends dorsa+posteriorly as far as the frontal- supraethmoid suture (fig.10) and ventrally as far as the vomer- supraethmoid suture (fig.6 ). The eectethmoids are in contact with the edges of the ventral surface of the supraethmoid and curve posteriorly from it on the surface of the ethmoid cartilage (fig.16). MeMurrich ('84) says that, the supraethmoid interdig- itates posteriorly with the orbitosphenoid and as my figures show, this is effected by posteriorly extanding spicules of the perichondrial ossification on the ventral surface of the ethmoid cartilage, as the main parts of the two bones under consideration, are widely separate (fig. 16 © TM O96. ee © Ch: iS ee _ oe tg oa Bik P94 Pischs att at .dohiw ,eqailexas fs fot aed WOR. ” pitebe sotovenert A. .notnet sOptetas eff i Be ett eft Te afutined sdt evode epste am 09 ett Be abiges a batt ag baw wifseeroh dtod ened edi vd egelitras edt Seeletec mrtyen fecantetat edt to nistsn sol reteoq oft ah by i fesce fevtuey aft ov clisetob ehnetxo JI af v git) opetivseo ‘ea | Yo soivetviaibiet«! efit es tat es uoltsultgeso iseteh eis to , t Sie Do roOls sid ea sbnetre Ti gt lextnrel -bfaetaort od? atin ei sidt .(..20) ptoncdacotidto ott as vitelteteee seas étasro | ure “igs #8} to hes troitetine Ae tae J mauce dente e* iobeseMell 4 tiube of? ut Selttevom ettemes ertel aid teq eat ina Dlomdicatuve sft ,asmatot crotogtfe att: et tolvesns — Peosa od? to (lee add a! tigboredlt tiie dese Ko Mr £6 edd at notner etd? to nolbttined. eft Adee Boe hseqeey Bromivestiatse sit to soltteoiitees edsotete eworde i & sit) meric eff 10 Séeqolievel 4¢ tue , isi bone ieee beams? agoe ext MEaws < pared bensmysi orf (2h o ge. LB TAL ove sawn Pr) to. Ie -fassori er? se rel ga “i eedavdaoh Sinevee: Bemod. ont oat ’ A ivmey See | OP sak) o7nd om blondie tq0 Me B Pepsinae s obtomdiases ou? .( 2 aU) suet BiemMeamgI Hab blog "es efy to sopttwa fantasy ede’. te sopte ext tte. @enitixeo bi! “6 sostive sit oe 22 tent Vieieer _ ptitedei bi ‘cent ,tadd eyeo ()8') dotumemmely TRE. we Ser fonaitqsetidto ot? Ata ulrotvetece” | yAroltedsog ¢é Heteetie ef Biiit 4 ‘orl tive [ete tev ett co aobeeakhiess fat HOO oi EO0G OW ed? Io sited ie od anys ‘( 35.2%) Sin teres ~—— eS gy ®t 91 Comparison of the longitudinal section of this region of Amiurus, with that of Amia, as given by Sagemehl ('84), shows several important differences. The solid cartilage characteristic of the ganoid internasal region is present in Amia, and there are no ossifications in it. The ethmoid, is a dermal ossification and lies near the dorsal anterior end of the massive internasal septum. The cartilage beneath this ossification continues poster-| iorly as the solid tegmen cranii, whereas in Amiurus, the posteri ior margin of the internasal cartilage ends dorsally at the anter- ior end of the frontals. There is no perichondrial ossification present in this region in Amia. The premaxillary bone abuts against the ventral surface of the anterior end of the cartilage, there being no intermediate ossification, such as is found in Amiurus. Nor does the vomer come in contact with the ethmoid, but since the ethmoid of Amia is comparable to the dorsal part of the dermosupraethmoid of Amiurus this condition is not remarkable. The ossifications surrounding the ethmoid plate of Amiurus have invaded the cartilage, while all the ossifications in this region | of Amia are dermal. That the cartilage has not entirely ossified in Amiurus is evidence that it has advanced but little farther in its osseous development than has Amia. In the Characinidae (Sagemehl.'85), another of the lower teleosts families, which in American piscine classification (Gregory.'07), is closely allied to the siluroids as an offshoot from the lower branches of the teleost stack, the ethmoid region is comparable, to a great degree, with the condition of Amiurus. The internasal septum, except in some of the very lowest genera of the family, has the same relations as in amiurus. The vomer to aoiget aidt “to Moitoee ten bid ba awods ,(28') Inomagat ud “ev is se aaa nee % By ; ri i ay Otrn eved? haw sims ai tnesetd ef nolget Tomanotes lila bg red ini sasli¢isco Silos ext ce oneteRe aMoidsviticeo Cemteb e eat . bouts scat rT mt entare iensaxei a? evtessm ens To Dip tol irevae isevob edt Teen > b—-Sutacr seuntince noitsoitieer sidt deseded egailtitse eat aes tsetsor edt ,aciuims nt eaetetw \tinato-meiget Slee) eat ee atatan pdt z¢ yiiseroh sine sgsiitrcss iséibnged edt to. M@oivacttiesc Lainbaototved om el etedl » seistaosh et Te. da encod ytelliganeta ex stad gt solges eidd al i ; (SRelisise od to ‘bee toltetas odd to eottine iaxtaev ot tea mi Bavet ef as dotre ,nmofisoifttego ote heated mt on sehie Gud ,biocdte of? driv testnos a1 emoo tomov ent geod eam) edt to tteq Ivetoh edd of sldeseymord? ei ae) wiiane seidegiomet ton al nol¢lbnoo aid? eutrimk De Bae ae : . eva. arurlcA ‘to eteig bhicutitg eA? galbareoras Gale 1 : : Bofae: otrit nt enciteoitiveso edv Lie oiide ooivenn ae | dbeitiass it tivae Jon aed egelisceo ed? teat - Leaves ous. A . teds1at-oefytil tid Besuevbe sad ¢2 jade eonetiverae: eotw tebe | -cit, sed sent teomolerel) apeeee ath ah - | rewoi on? * aivgona .(ca*.fdemeups ) osbirtoatet®! eft al noigacit » oficelq caobiems ni dete oot fimst eteoetet i htorgtte eft oF Bbetl(s vleeate wi,{90" pgs 206th Jeceie? aft te conomp id towed eft: ont noiw ,eotged teem alee .*énvermen: mk z ois to epee of iqeoge mates een 2 an -cuxclaa “f 68 shotvelex omin ene game pidick a) ie | i 4 ¢ 92 is usually more massive and extends in ventrally between the ethmoid (Sagemehl) and the cartilage. According to Sagemehl, the ethmoid has a double origin, as in Amiurus, the amount of ossifi- cation varying from the Amioid condition to complete ossification of the internasal cartilage. In speaking of the ventral extent of the ethmoid in this group, he hoped that further investigations on other groups would justify his coneclusion:that such a condition} did exist in other teleosts. In the Cypriinoids (Sagemehl.'91), there is more or less invasion of the cartilage of the internasal septum by bone, but none of the species have proceeeded as far as Amiurus in this respect. In this family the ossification around the ethmoid cart-| ilage has extended on to its ventral surface arid is here in cont- act with the vomer. Concerning this region Sagemehl says: " In Folge dieses Verhaltens k§8nnen wir bei Cyprinoiden an | jedem Ethmoid zwei Theile unterschieden: eine dtinne Knochenplatte, die amndhernd dem ursprtimglichen Decklkmochen entspricht und die lateral die Nasengrube tiberdacht, und eine von dieser Platte nach unten abstiegende mehr oder weniger breite, aus spongioser Knoch- ensubstanz bestehende,vertikal gestellte knScherne Wand, welche die beiden Nasengruben von einander scheidet, und die durch Knorpelsubstitution entstanden ist." This condition is also true of Amiurus as we have seen Hence the degree of ossifi-} in an earlier part of the discussion. caétion in the ethmoid region of the Characinidae,Cyprinidae and Siluridae affords another factor for grouping them together. Of the mail-cheeked fishes, (Allis.'10), Triglo has a part of the internasal septum invaded by bone, but in none does the dorsal ossification, either @ermal or perichondrial, extend over the anterior end of the cranium. In Salmo and most of the other teleosts, the ossification is entirely dermal and has no peri- chondrial element connected with it, repeating the condition gO LT ET ~~ h. Le. rh ee me Y - Ter ee ." a ae mi: ¢ rh ge a eft naenied Yiler tev at abgetze fae | edt ,idemegee of gabbtoosA .vaalitres otf ome a -ttiseo to ¢avome ed? ,emibima al ss wa.) . ‘obit Bt Roivasitises steLames ov nentihacs biota end ible mrceiec hs ditetxe Letiney ait to guilesge ol 4.epeliewes, ie | Sooitanitneve: « 7 LU $2 trait wore YE to eo lt amyos aft ol areth 2eT ad? elk tenor Beiaet sidc meet S7Hh of bo k* fear i _eTtIsl sm bri Tol 7 146) a, — Lo 4 a iy ff to ,tact Rated I enoehrequce sttaoittess to tasom sergrel ede cad out yoRIB ent ol vreabh ai =r. ‘i, i 1 ahi no 4 r at aie get sa -tSoqds ov cottaett tere owt edt to sets siden tad tigi obits teddke te esecesa Stom rogued® edd yenmiet Teptnoy IF seads te al aoitseltineo to aninoniged. edt bose bedi t Beh d oitlasc Loithacdgtved «Beton mes | tts toot syomdcé stad apt ede eLisw 4 | etercrg blondtetse aggrigedioxes edd @ il .tidto eft eveds. pitoieeper | of betseqrs aids esi Otipott bere Bie . sutrot dotdw seaiictes one to mage” atin ; eft 10 tree Dgted 6X0, emt ae 2 lL ateepeb 2 dtin tedérnr one Se ‘feetod » a6 SY ib. Jeoo ea i etre seted igi iuetas no. tnahhtnee tanta fog to toot add to eos bane foster eit coat St ,esid! «.lants wretes?toe ont erm? fs Aboot feean edt ot te0Lt wontgertesas Sennoo davot Las aged wel dbomera at es oldw noiteolPieae Le tchmod olzeq “<< ban onttaley odd 108 Open aelvoltns.e uit) Samevoort it omert Wee schol tecohtilese feraae v hae taoro . Tal nate oad oo win | | a! sLe0 72 6 08) tla tiw aelners, std XO cabo rev wh i | a TA ra 94 Purther contact between the ventral ossification of the ectethmoid| and that of the supraethmoid is prevented by a wide expanse of eartilage visible upon removal of the vomer (fig. 16 ). This figure alos shows the distance between the ectethmoids of the two sides and the very regular edge that each has. The are also separated from the orbitosphenoid (0S.) by cartilage. Posteriorly and above, the dermal ossification attached to | the margin of the bone, is indistinguishably fused with the peri- | chondrial ossification surrounding the foramen orbito-nasale (fig. 10 ). This dermal ossification is a very pronounced process projecting at right angles from the cranial wall. Its medial end is continuous with that part of the bone which, with the orbitosphenoid, forms the upper and lower margins of the orbital foramen (fig. 20 ). These are the main features that dis tinguish the bone. Its dorsal surface is covered with small ridges which radiate from the center. There are slso numerous nerve foramina for twigs of the ophthalmicus superficialis ttrige- | mini, but known of these are connected with a lateral line canal as McMurrich ('84) stated, because no such canal is included in the ectethmoid. The posterior margin of the lateral process is continuous with a Similar one on the margin of the frontal of the The inner surface of the bone is covered with a thin same side. layer of cartilage (fig. 7 la Cuvier ('28) called this bone the frontal anterieur and described it briefly in the perch. In his diagnosis, he said that it enclosed the olfactory nerve, was not entirely ossified, and had an artieular surface for the palatine and maxillary bones The suborbitals were attached to its lateral surface by ligament- ta 6 mI i" ba; aoa aad ent é reve eo! + te to Be tek "4 ve ty Meet! se a sidt .{ ag .3tt) tomer eft to Sovemming tdtes ' owt ed? te abfomitstoe sit gon med sonst i ali ale cafe ers eit .ved does tadt enbe sorte tenmb eae vobta ene 8 exefléase Yo novel | it enod edt Bel fno test} arene *h wx marst 2, tt ot sdoweg Gao linens dedts | cietivne Fon exw ,avten i [finer bus enlitelad ett 20 ‘bea erites id. WUC Ouosa HS Laradat avi od bodcaiita eTen 7 ae eo: 95 ous tissue. Except for the connexion with the maxillary, this description would apply in a very general way to the ectethmoid as described in this paper. Stannius ('54) used the terminology of Cuvier in describing this bone in the teleosts, and stated that} it was one of the marginal bones of the first and second head segements. Huxley ('64) remarked this bone as a development around the ectethmoid process in Esox, and, though calling the ossification, the prefrontal, he stated that it was comparable to the lateral mass ossification of the ethmoid bone of human anatomy. Vrolik ('73) followed Huxley in using this name. Its synonomy may be found, in common with that of the other cranial bones, in tables given by Owen ('48), Vrolik ('73), and Starks ('01). Vrolik very briefly describes this bone as a "yerichondrostigche" ossifi- cation, that is, what is here called a dermal ossification. It is figured for the carp, Silurus and other teleosts, but he does not discuss it farther. In the Cyprinoids (Sagemehl.'91), it encloses the olfactory nerve, the ophthalmic branch of the trigeminus, has an articular facet for the palatine, and is called the prefrontal. It pro jects| very abruptly from the lateral surface of the cranium, separating the nasal fossa and the orbit. Its developmental relations are not discussed. These same relations also hold true for the Characinidae as described by the same author ('85). Gegenbaur ('78) calls this bone the ethmoide laterale or praefrontale. He distinguishes two parts, a lateral and a medial, the latter is developed from the ethmoid cartilage and forms the inner wall of the olfactory canal. He claims that the area La ety seis = * a abot atid ‘od yew “terexea wey sl qaolehintet eit Beer (4¢") adtnmete ies ft betete fPne ,stoceled edt mi sitod ade Seed Saocer ote tetit sat Do eonod £ §em2 Savote orp ze Leveb & b& GROG eind | swotteoltinec edt uati fies ggeny ina | | af faretel edt of of8excimed egw ot tend asete on 52 | Mifex¥ .yootvanh neovd te ‘pntodi Stoantte oat Yoe t ( ed yem Ywronosye dtl . esa stat anna ie | eels? ni ,eoncd etdets teddo ott to, ted Ae nnn ie ’ Wifoty .( 20") egeete bas (at) attov , om a ! = fhiseo "eipeit acthaodefteq" a as endd mt a ti .moitvAcfiteso Lagteh « fellss enon a i at Bodh ef tod ,atedeled tothe Sam acre) ah Migeetlo eit sesctone th ,( TC’ yfeémee bie = } we ee as rr ,auoimoni«?s edd Feéotonaead cin Ladedeo ate, ; 7 4 7 “4 ef * t j-- + a 8) Béselor; +1 «. Lstnorberq fd belies Sh Bme omtoalag ae Bris: Tea7es cy inet: oni “o 6ostinve [atetsi ee wort ) @ts Ancittel[ox lLetrenuvefeveD BT. .dieaaeee fine soe san ecg wor diet hbilod cals welisietT emae onedt pees | | 4 .(26') todtse emnae eddie bodixoneb. 6 J . | aleyesoi eblomiis en! aged gidd’ elias 0) ae Sel | | (8 bine Loxotot & jutzhg OWd vedatgeraanD aR vt br r Bre ore. isvaico Dicthite eid hort ahbadethaet i | eh a ake ¥ ee 7anrs onlale all Pee ted 34) Yrotoetile ot! Xe 4 aye pit y rey oS o rx 96 sculpturing on the dorsal surface is arranged concentrically and that the ridges represent lines of growth. The bone does not have| the extensive articulation that it has in Amiurus, but is limited to the cap of the ectethmoid process. McMurrich ('84) made two statements concerning this bone ‘in Amiurus, which contradict each other. In one place (p,277) he says that the upper surface of the bone is very irregular and has numerous foramina connected with the mucous canal system. Farther} along in the same paper (p.280), he says that there is no oneal between the ectethmoid and the muscous canal lying dorsal to it. If the first statement were qualified to mean nerve foramina, as I think he really means, there would be no confusion in interpret- ing his statement. Since there are canal foramina in some of the bones of this region, this qualifying statement should be made. Gaupp ('06) in remarking upon the development of this bone in Salmo, calls it the pleurethmoidale, introducing an entirely unnecessary term. If one standard of nemenclature is to be adopt- ed in comparative osteology, it should be adhered to as far as possible. Anyone reading Gaupp's papers is at once struck by the flood of new and unnecessary terms throughout all of them. Accord ing to this investigator , the ectethmoid of the adult Salmo is a true perichondrial ossification formed around the planum antorb-| itale (ectethmoid process). The adult condition is the result of endochon@rification and resorption, with an added ossification formed by the ligament connecting it to the palatine. The bone includes the ophthalmic branch of the trigeminus, and the anter- ior ossiele of the infraorbital chain of bones is attached to its lateral surface. wil | ap. Pa ka ete Bi 0 st ba rt * - vod eof aoed oped od? .dénory to cont (hee —a/er Seamte | Ksnneenie Betiat! cf ted ,arveins at ean t) tad? site: isi Tar % ened etae gdiarsenes atepneteda. ow ebsm (eo") | | m ee (TVS.q) eovla eno al vente’ Aose tothsttane doltw 44 eas fae talfeect: wrev &f onod eft to eostme am | eiits% .meteye Lanes avodam ef? Airw Deteeunoo ckmerot iExemroe on ef gu tedd, tad | BERS et (0eese). ‘teqed euise¢ it Jl ot LInexoh wail Iekeo axooere oad sens teercorebiaillias as .Soimerct evren noem ov beueteamp” ergs Mas etetqteiui at nolevtdoo on ad bisow qaeth- renecm Yileet eff : TO omoa of animotet fants ors srveqt Cla dnemedede a! Oba od Binotte tienedsia an ibe aie tds yewinet onié 20m eaod utd? tc tosaqoleveh eft coor writer at (aor) cuted viecitoo us yatebicrtet Lofpitomdaeaaeanae at atten, ont sewed to brebtade Sie Ee uae + HA ) SA $8 In the Amphibia,Reptilia,Aves, and Mammalia, the nasal bone Qccurs as a dermal ossification on the roof of the nasal capsule. In some mammals the cartilage of the capsule beneath this bone disappears, and a condition comparable to that of Amiurus results. The teleostean nasal bone is comparable, then, in a certain degree| with the nasal of the higher groups. In nearly all of the teleosts however, this bone contains a lateral line canal ossification on its dorsal surface. In Amiurus the bone is isolated, but in most of the other forms it connects to a greater or less degree by suture with the surrounding bones. The lacrimals. A single lacrimal on each side of the head forms the lateral roof of the nasal fossa (fig. 15 ). Each is very small and narrow and contains the anterior end of the suborb-} ital lateral line canal of its side. The most anterior dermal tubule of the canal issues from the bone through its dorso-medial edge (fig.11). From the small central part of the bone four proc- esses radiate, two anterior and two posterior. The antero-lateral| process is slender and curves around the external margin of the anterior naris. The anterior end of the suborbital canal after leaving the main part of the bone at the proximal end of this process proceeds immediately to the external surface of the head. The process is closely connected by ligament to the maxillary and premaxillary bones, and to the ethmoid cornua of the supra- ethmoid bone. The médian anterior process of the lacrimal projects toward] the middle line of the fossa roof, posterior to the anterior naris. It contains the first dermal tubule of the suborbital lateral line canal, the pore of which lies lateral to the pore sic oahu hd alah “vetwanee Heid wad 06 S00 ost sig pare : © nod abit ddmoned efvaqso ext to awl ieee ‘ i see ineex esx#imh Yo cadt of siderequos n0 Xt. : ot : o5 aisives 2 al ,fedt . ofd atagmon at 10 pene ler edt to dis ylused AT .éqsots Ted td nO moisoltiese fagee ett feaptel 6 saLabies -@s0u at tid ,fbetaioet al smod ott —ar Yi eoTae5 seoel To Tetsets sot pe i mone | -soxod palbaroniuss “bsed ead7 Yo ebia desé ae Lamitoal efoote: rad esas * eit dosh .{. ai .mit) Senot faean edd tak ae mete $ -Gtedse efi No base toltetus off aint atmos bas woven So fatesh xotre¢ne Yeam od? . ei sii te tagso eat ta | fatbem-catoh ett cavotdt enod offs mary vorvet. Deaio abo. a ‘art . -petq toet omed edt to tteq Lartetes Ofams edt pane’ pha. Teredsl-oteins ocT .t0! thet Ta owt Are xorredas ont! 6 pee ty “ies ye ‘ efy To ntatam Lanredys eft Daticts eorege bos gic ete = ui re Wa Bi, - Tette Ianeo Letidredre ont tone aoltedare eit “ Siig to hres Lamtxotq oft ta snod sat Be traq a Bae ed? to exeitne Lefred xe eft o¢ qletelbeaut | abs . xisilixyem et ot toamantit yd betbenkeg gleroto or 7 7 -etqut od’ to ennitceo biomite edt of bas .Honed Y vy i a isl ae ‘= KG tolcOtan ef? ‘62 wel red e6g TOOK a8 6% poe tay Ietidtodve edd te eiigud Lenish Yona ot i we ow. of 4 | hig odd of thretal ebtt dotdw to et04 bake } betawoe sgcolLotaq Lenlton! eft to sperexd ToL? ae _— a ——— SE en = 2 = >i ray 100 of the first dermal tubule of the supraorbital canal, posterior to the margin of the anterior naris. The elongate median posterior process extends posteriorly toward the anterior face of the ectethmoid bone. It lacks a lateral line canal element. The anterior ossicle of the infraorb-| ital series of lateral line canal bones (fig. 15 ) is connected with its ventral margin by ligament. The lateral posterior pro- cess of the lacrimal lies external to the first suborbital bone, so that the suborbital lateral line canal enters the posterior margin of the lacrimal between the posterior processes. After giving off the dermal tubule desribed above, the canal: ends by the passing to the exterior.ofhére isronensenserorgan, othe most anterior ofthe suborbital lateral line canal,contained within the lacrimal bone. The nasal bone encloses the most anterior sense organ of the supraorbital canal. The older writers-,Cuvier, Stannius, Hallman, Wagner, Huxley and others- recognized theslacrimal bone as the anterior element of the suborbital or infraorbital series. In most of the forms studied this bone was the largest and gradually came to have a greater morphological significance than the more posterior bones of the series. It contained a part of the suborbital lateral line canal in most teleosts and Amia, and was usually related to the roof of the nasal organ. Where its development has been studied (Schleip.'03), it has been found to arise primarily as an ossification developed in connexion with a lateral line sense organ, and later has an osseous base formed from surrounding In Amiurus, as noted above, the lateral line connective tissue. element is the first to appear and the dermal part does not / qizoiteseog ebadixe vessety Tatteteor 2 = ex nae ) ea? | j is sg on 7 _, 7 & Gfeal @1 .saod Stoamitetos eft Bo. i" yan ye “ ’ re ay ata oo : | bitecxtnt edé¢ toa sitiggo tobzedae ext im WP BiGetesanos vt | Sf «.nit) Beltod Leaeo Pee : “OI¢ aoiteraed larstel ont inomegit ua Migten £ : sened Levidrodve tetlt aft .¢¢ ereerens eolt isabsoat 10 tuaitaod eit ated Tere osnht Covet Ind tdrodte hi “fs - sects .cynuscotd ro tteteoy el ngewe ee Simtroot od? 0 a a” wd eins cieoes ofy ,avods bediceeh oLudwi cam er tt » @ Peomied?: ,dAsnto edésetrane™ er etonto. robsetan edt bl | | Midjiw beniatnoe, faces enmtl Lecter istidvedee ¢ qolyvetas taom eft uoeolone eitod ignen ei bad fmatcoat .Laned eh ev beled pra qoixnh, tenas ,nantlal .esrtanape \-te by fmemelo zo htetces eft af eaeod {et xoe tnd Som dameow oe SH10% eit to tcom al .ebtrot Letidegeetee xe Ens brosue | B eved of or wilavbura ioe Teagted od ag’ ociodt nink bert } Sencd tolcecnyn eTom ede Get) Spm scltigute Sev tye rodent Tota “ mt | [oretel Isiidiedse edt to trae & Bem ieee Bolte ong 9 bevaler ylissas saw Bas obo bits evacelet. Peon at Annee Seed aan dineiotLlevod etl etediW .tenre fapen ine . | tlitamt{ iq sevlis of hegot need can, #2 hie ratensen:. te te peren omit leteteal 2. Atiw nébxbanbo: of hoqnieves ottectt ceo ae * ilLbavoptits mott bemrot sand oy oocan aa et eabas q eal a? - i. . onl [areveal of ovods. heaton bah Sit A ah 4 ° ‘a * pie 4 %08 coeh trea Lomtel ost bane thegge OF Be Z » ie . a 4 101 ossify until,much later. I am satisfied that this bone has two parts as Schleip has stated and that, the dermal part may be bane! logized to the lacrimal bone of the higher groups. As the lateral} line canal is associated with those forms which live in the water, | so is the lacrimal canal found in those animals which pass most : of their lives in the air. In both cases the bone develops Later-| al to and usually dorsal to the nasal organ and is a dermal wee ication. It may have more or less connexion with the surrounding bones - nasal,maxillary,premaxillary,supraethmoid, and ectethmoid - and in some of the fishes with the vomer. Allis'('98) erterion for the homology of the lacrimal is the inclusion wihhin it of the anterior end of the suborbital canal. In comparing his work on Amia with that of McMurrich on Amiurus, he concluded that the antorbital of Amia was the homologue of the adnasal:(laérimal) of Amiurus. Since however, this bone of Amiurus contains the anter- ior end of the suborbital canal it is the lacrimal and the antorb-| ital of Amia is represented by the long antero-lateral process, which has fused with the lacrimal element as it has in some other teleosts. The frontals. These bones are the most extensive and con- Spicuous bones on the dorsal surface of the cranium, forming most of the roof and part of the side walls of the cavum cranii (fig 10 }). The onlg point of suture between the two is in the regioy of the original epiphysial bar. Anterior and posterior to this Suture they are separated from each other by two longitudinal fontanelles, the remnants of the more extensive ones of the young- er stages. Each has a raised margin on the sides of these fonta- nelles thus bounding a fossa which continues anteriorly as far ‘ . wa. b iid m4 y ead esed 1Me ved Hertedese me F or > s: - dal tiie sé gan dean fneweb ett \?oK? deo Soteie MeN Mbettbe es: (ol a ite ee Kevstel eit BA -.eqrors tered eHt te enod 7 “eo “ ot 1 ee , ‘ie if . ; 7 7 7 ¥ s (seten of? om! evil dotdw smxvot eees) aviw Bem is ei Lens. en ; #e6m eter coldw elenins eset at tarot Dames centsont et cB peek lagoteved sxod siz satan dtod ri tie ef? ot wel of pal steve femteh o ci Sas aeyvo Lepen eft ot Beneed: vitanen tae at afiimotics ei? ctiw coixemeoo eeel <6 Siem eval me cet Blomifatve hus , Stomiseatqie ccs sealant @ebveix® (B°')'alllA .tasoy att ely eqtett, aieae omoe me & | Re vt aiddiv sotarfort edt |2 Land tome out tor epotoasd of Svée cid selieqcmes al slaseo Eat idcodse od? Te Bae comeans © d eit Yes Behnicnoce of ,arceiné no Dolueiiet ts ¢adtt athe ; a rm aor Lad 1s S f ae 7 } = a So (Lenizéel): [eecuhbs oft to exgetomed. ont Baw abe te fetidy BS 4 : 2 i * : : ay -vetnes oeld eniciuce souls to éfed wkd? . terewod eonia .8 oa o advotue oof bow La@ltont adv ef ¢: DewgoeDarketodee ease bse 1 Su ,eascotg Imvedel-orevae soot ody yo tetgesetget Sf eima to. ‘ tedtc emoe nl sar tt se tnohele Lemfcosl edd ere Geen eee o . 1% t 5 .eteontes. ata nt -hGo Bas evlucetze teom est ete comod eae .ofetmert edt: —ae } ¢som Suletot ,coluete att to sortase Ledeeb ade ne Seemed euosolqe: eit) tiueto rurvec 6c¢3 To alfLaw stro ante oe ot2q Sar toor odd Ye < | Oi9e7 «6 ’ ge! ow? of? seewiod etsire Zo trntoy gino. est sly of teltrea@so, fae telgetmA, .tad [eleyiaige Leatgito . fanthotiecel! ons ud tentto Agee geome dutetaqes OTR gods ' ] -BaV0 od? *6 temo avisneixs otom eft 3 etek seal i ] seGact esedt to ueble eft nO Sista teazet 8 | Tet on “ito 'ietoe eousttnoe Molde, seeeey 102 as the supraethmoid and posteriorly on to the dorsal surface of the supraoccipital. This fossa is filled with connective tissue and nerve fibres, and a tough membrane is stretched the entire length of each of the fontanelles. Their restriction is caused by median growth of the frontals, a process noted in its incipi- ence in the 32 mm stage. EHarlier, however, the posterior fonta- nelle extended between the anterior edges of the occipital arch, but the ossification in this region has grown forward and closed the extreme posterior end of the fontanelle. Anteriorly, the frontals interdigitate with the median sup- raethmoid, which forms the anterior margin of the anterior fonta- nelle. This interdigitation lies above the orbito-nasale foramen and is continuous laterally with that between the ectethmoids and the frontals (fig.10). An oblique frontal ridge along which the adductor mandibularis muscle has its origin extends posterior- ly across the dorsal surface of the frontal from the lateral posterior margin of the ecteéhmoid. The frontal ridge does not extend to the posterior end of the bone, but unites with the ridge which forms the margin of the median fossa. Behind the union of the two ridges a wing of bone extends laterally to interdigitate with the sphenotic. Anterior to the ridge the surface of the bone is sculptured in longitudinal ridges, which run posteriorly toward the middle line of the cranium, parallel to the dorsal margin of the ridge and extending along its anterior face. Poster ior to the frontal ridag the bone is comparatively smooth. At the anterior end of the frontal ridge the suborbital lateral line canal enters the frontal pone from the postfrontal (fig. 11 ). The two bones are not in contact with each other, so inl a * ee | LUMn eis — Ae So eostiwt Issteh add ot sto wire oly eta bp Su erenit evitoonion Adin belLtt #1. seact . re hh \eritde ott bedotdate 22 ecerdsies 4evod oBme (eer it rre re Sesues ei soltoistest LtoAy net Lomatnoe + oft Benge: toh ak -itgqionit eti mi beton avengsg 8 ,elatacs? edit te Ktworg satan -“Biaot toitetece ont , tevewba rolltat -ogede out 86 oat at 7 adie to: seeBe «x6 trodits ene neowtod hobastxs pois Begols fus Siswict ovoTg sad BOAgot eidd mt ‘ROT ERI a -cilenataot edd to bag xo Preveog eats asifem sit iviw otetisibt tetai eledaott ea? wee aes ~e¢not rottietus att to wintsm reisedus: out! enro% foltdw y gemosct efssan-otidto eit svode estf woltsdigibuetas aide ebieorivgetos sit ntsewted fart axe sper: suo ttape os . Motdw nicole ogbit (Cetnovt sooiide MA” «hb OF git) ‘ale tnoxt | ante sale Atéixvessog cbhnetxs cigito eti sad sloakm sbwind? bran covet wievai aly aortt Levabs3 eile Te ecatige Laerob edi eeotos xX tom avvb exbix. Letnoid odT . . Dkomisétee ode Ge cigrom tobte: a Senbizt ait dziiw sesiag tud. .,eccd edd/Ie Ge tO lyetacg” od 08° baedde | 30 folcs oft bainei .saeot asibem ont Te niggee eee erro odd , @vetinifxecal cv ylisxetel shastxe enod 6 aati’ a OORERe One edt. bit “Lo etolyse oft ephit edd oF teiTehmA /eiReRenaS 6nF dt tw: citetrest co: ofiw ,@ostit’ Lactigs taaod ie he tat Liroe ed éabinn | Ja faetob occ ov. Lollateq ,mvhoero off 6 6h Lee edt Bean | | rlhuedne bee embdss odd to os | ‘Miocer Yiaviveseqnoo ef erod edd gebee batnost i ott of tod) | ' | =a © | re rm + - p= eg ee _ 4 = fevidtodye pt eebix [atuort of¢ Yo Bas retredus ‘oni’ on a, fatrovtiwou eft mot? onmod Ietaor?d edd egepae- ve ‘ontl” Latet os , rento fone Ae J W Joo al von 78 aio owt ‘eat A | att | 103 that the canal crosses the dorsal surface of the adductor mandihu- laris muscle before entering the frontal. A dermal tubule is geven off from this part of the canal as it passes from the post- frontal to the frontal. The frontal bone extends down into the wall of the orbit externally connecting by suture with the orbito- and alisphenoid ossifications (fig.20 ). In the anterior part of the orbit it is separated from the ectethmoid bone by a small remnant of the fused alisphenoid-ectethmoid cartilage. Posteriorly it interdig- itates with the anterior end of the sohenotic bone, above the alisphenoid. On the inner surface of the cavum cranii, the front- al descends in the cranial wall in front of and behind the line of suture between the two frontals, but immediately below the sut-| ure this down growth is limited by the: dorsal parts of the ali- and orbitosphenoids. Anteriorly it overlaps the orbitosphenoid and continues as far forward as the cartilage which lines the cavum within the ectethmoid. Posteriorly it overlaps the ali- sphenoid, interdgitates with the anterior margin of the sphenotic and proceeds dorsally toward the middle line of the cranium to : interdigitate with the supraoccipital. There are many minute nerve foramina and canals in the frontal bone, but none of them reach the cavum cranii.. The larg- est canal is that of the ophthalmicus superficialis facialis, which, after issuing from the alisphenoid, sends a branch along the dorsal median wall of the orbit and is enclosed within the frontal: It continues forward within the bone sending small twigs dorsally into the bone to the lateral line organs (,p+.4;neq OP si, in it and also clear through the bone to the integumental sense ‘de ee oe wor A fen tetorSha edt fo costs deetod effi o Insao e P : Re okoan st elwdpt Lamreb 4 '@. se ded -teoc edt mozt sennsy tt 2a) Lama) eit SO: aap | . - ptaon" Diba uitis 2ids0 exit to fisw ey ofmt vill ebredee wed teduosy a rt Bionstusalile baa -ctlidte afd ' dtin ewudpe yw Bit Dexttoo | e o ¢i tidto eda to dueq toleetae eft al al <3 ee eid to tasawot [fame 2 46 emod Bt sitotee ent mort Beds 188 5 L Mette teehee ot evltoe be f @bloneg «ii to deom bas iteoclsy Y¥Teve vileolsoury al rabbendion } * Mrlaeto ede to eonitey feetch ost do Rend geugteeame exe: yard: cellouatnot | bette pliatam etait Yex ty fio iptvod Qé etepetet eat a bexiagooen, stitnah sccelet tewol Yeém ‘Sie whey eet eee), antonset betoennoo ote a tavactt on? Jas theeds ete sellonstgen do goes ortine angst: anole utuine’ tc afLotoer> eft a2)w soebapqmos Ce M ‘otml bee Ullvntdov ¢qnaeseveh te eagkte c . 7 eh me t a a 0 AY 106 cover more of the dorsal surface of the cranium than those of Amiurus, but they take no part in the wall of the cavum cranii, being sevarated from it by the solid cartilaginous tegmen cranii (Sagemehl.'64). They do not interdigitate anteriorly with the supraehtmoid because of its limited development, but their rela- tions relations to the nasal bones are comparable to those of Amiurus. In the orbital wall, the frontal of Amia is separated from the orbitosphenoid and alisphenoid ossifications by cartilage] Cartilage does not extend between the frontal and ectethmoid (prefrontal,Sagemehl) as in Amivrus. In the Characinidae there is a mixture of the condition fo found in Amia and that of Amiurus. Citharinus (Saremehl.'85) apn- proaches the Amiurus type of frontal development externally, but is more like Amia internally, in that more cartilage persists in the side walls and the roof of the cramium than in Amiurus. The epivhysial bar is not enclosed by the frontals, although they meet | Sarcodaces lacks the anterior fontanelle found in Cith-| above it. arinus and the posterior fontanelle lies more between the variet- sls than the frontals. Internally, ther is less cartilage than in Citharinus, but the epipvhysial bar remains unossified. The other families of the lower teleosts - Mormyridae, Osteoglossidae, | Clupeidae, Gymnarchidae and others = have the frontals connected by suture as far back as the parietals which are highly developed The internal felations of the frontals have not in these forms. been described for any of these lower teleosts and it would be interesting to find out how much cartilage remains beneath them. In the Cyprinidae (Sagemehl.'91), the frontals have rela- tions which closely approach those of Amiurus, but the anterior a toy Boi seed anid “i jaune te - 4, fa ” ’ = - Ee Ne iealoas JOU VRO oi to isa ond rr seat W + i“ My ‘*Pnerve mews? siforlaslitaso Bhler eit ooo 0 feotaret a 8 ede dviv Ylrolietne efetiggbtotal tom © “M96 tome -alex thedt tud ,tuevieolLeved Betintl eff Ee to cenit of oldsraqeos ets senod [seam yade of Betersdee bi sins. yo L[atnort cent the tne ta easittvase yd cstottaoriiaeo Sloactaul Ls plomfitetoe hos Istaort ed? noawed Gaetee eotsrigia mh en t 6% notdbhawos ed to otvtxis = ub erend ae ‘ cote (28'.Ciemenet) sgituadt?® vemtebea ey path | BO . ded ,vilentsies teemyoléeveh Lasnew? te omey. eopapnk P evetereo easliscac eton tedd at tested abmk 6 | eff .ewrolmA al aadt ogbnero etd Teligot sit Gan Gh Hoon vod devortic ,alstnort edd Wh SepoRone Cem/ak! } il poe Beserd af bacct, efleneteot tet veths ett “Rear ‘seoaboorae } ; («2eiisc et coewied sxem eal! ef fagatret no ltatuod ¢ a noid eantloiss seel eb tect tf tentaseer .sletdor? ed@ ate Re}. eee : é q ac boltfarogs: enianet sed. Lafeydyigey Gee eae soublenolacetnO ,eablxryare’ - efpoeled semi ale to eeatine Fedvgoorro: taorlt ef? eyed .— e7eaeo Sie seolevel vidald ere | otal tlatelteq eid Be ane Hea he: $6 OT sludwo® on} to eheiveko® Lecrsoitah age -omxot od Liuow tf 5he eteoelet towel saedd Some ee : bee enianet eysllétoe tou vod tao batt ot ead Wid wfotnork odd | (Reh. ideonaaey “ onnseanieyh eae: a " jae oft tod ,emeattmh te ésont tadtinin aR — —— — 2 iat v= aes amare y os _- 107 fontanelle is always closed in those genera figured by Sagemehl. The epiphysial bar persists as cartilege ini’ the adult and the frontals have not extended beneath it as they have in Amiurus. In none of the forms thus far mentioned have I been able to find a frontal ridge for the adducto mandibularis muscle comparable to that in Amiurus. The postfrontal (sphenotic,Auct.) never has the | dorsal extent that it has in Amiurus, but is always overlapped by | the posterior margin of the frontal. | In the Salmonidae the frontals lie superficial to the teg- men cranii (Parker.'78), as they do in Esox (Huxley.'64) and take very little part in the formation of the orbital roof, probably | because of the persistence of the cartilage in this region. Fur- ther discussion of the topépvathios? reletions of the frontals is unnecessary because the above shows that there is a general agree- ment in position throughout the whole group of teleosts. The relations of the nerves to this bone were neglected by | the older anatomists and not until Sagemehl's description of Amia | were these studied. As in Amiurus twigs from the ophthalmicus superficialis facialis (Sagemehl's fifth) pass into the bone to innervate the sense organs of the lateral line canal. In the Selachians there are a series of foramina in this same region penetrating the supraorbital cartilage (Gegenbaur,'72. Wells,'17).| In the Characinidae the ophthalmic branch of the facialis has the same relations as in Amia and Amiurus. In Amia an anterior branch of it extends dorsally through the cartilage and frontal at the anterior end of the orbit. In the Charscinidae, Cyprinidae and Amiurus, this branch passes to the dorsal surface of the cranium through the frontal alone. In Amiurus it lies free in the pti esesich y! S. eure YS. > Wet oy 0] ee ‘ial iit dh polo voictiien Des LOPS aad eaf foe tinba edvint ene l lines ae ote. j ua) i * ; Di he RRM Rage « am | ade ntdtte ‘orseotions. dda enoens to Lataert ed? sort elietinev «faaeo & miei be evren oft eaoteand cr. +» an: ea Pid edt tuo atow of textt of? to ano cow TOMY & Raw gre dt emlg ati ot qi .#Eatne+tt sit be Seqofeveh sew ornd edt tant tAgwodt ow oor, te wetiey slow oft svodssottit efdstaqeoo orebeteat ‘baa ie 4 #2 sifemmall bose seve ott at tet? bied ofF @Reae: bem jioedaes'e f, Get efdieworse: saw {¢h') dredotet atin nT ot tree: id mock ¢1 doot teil nov Bae susmetete 1 ed? .nisyfans isotmato baa Isoigetodedti, ee Ye tevortses | add of sesut os aved toh 5£5 of todd hewotla eued-wdt Re, etoylane. Bi .opeatiivso mott beqofeveb eegdd eft et) SD nitbando, edi Eetcortt edt sedi soften esos eds ot enpo ab grew eid to #f Byi¢oerncs [arnreh mott beaoleveS aew agwota ad? Me tosiswond ‘ swtvisebnu eit dtiw taemgoleres At OB oF suistos bod ‘Basi reek i ve d 6d to sosmatlevebvert so semtorespet taonpeedye.s, | atkins | [25') «xccdxrened bas (8¥') givtecR - ppatemedepe, ee 0 enred 4 eeLe: eiteh evew semod fLetiortk eit ¢Sinclstonrtnahieeenell | Sign’ | ues eved se_aeds oFtanenetgie Zo ata | ‘eeliocloA .eoao evopaso Bifoe s otat Benue Bas nottleeg tm ol? ovetw egete thotebttbab edt: costae seemed Bem : | betelvoor 4 an 4 aneo em@lf fewetel {st léveetgoe dt . 4) ow vi ‘a e7eastc ii BVvVece~.aey baie sh) onan ait? al sn0d Letaort edt diay Pa es ter > encod easy 26 eoebtus feasted eid 1 ReTOY Wah TO rae cee en alt bue woerste laseed fat aneR old al (BRD) ator¥ a te scanod! ietuot off Yo gnemgoleveb. edt “reeianiiinse —— a'r [SS er sane “4 >= Ff ar de ie ip . 109 teleosts, states that the frontal bone is developed primarily to protect the canal. This has since been refuted by those who have worked out the developmental relations of the canal and the bone. The ossification around the canal is at first entirely separate f from the anlage of the main part of the frontal-~ Klaatsch ('95), Schleip ('03), and others» In Amiurus, as remarked earlier in this paper (p. ), these have been noted as separate ossification@| In brief, the frontal bones of the teleosts are paired ossifications arising from fibrous connective tissue. They may lie above a solid cartilaginous roof or they may form an integral part of the cranial roof. Anteriorly they usually interdigitate with the supraethmoids and the ectethmoids, and are separated from] the nasal bones by a connective tissue bridge across which each supraorbital canal extends to enter the frontal. Posteriorly they | usually interdigitate with the parietals, but in the Siluroids the parietals are not present as descrete ossifications so they interdigitate with the supraoccipital. There is commonly a fonta- | nelle between the posterior ends of the bones, and in Amiurus and some few of the Characinidae there is an anterior fontanelle as well. The frontals overlap the orbitosphenoid and alisphenoid bones in the wall of the orbit, both internally and externally in those forms where ossification has proceeded very far. They also contain foramina and canals for the passage of the ophthalmic branch of the facialis to the integumental sense organs on the dorsal surface of the head and to the lateral line canal organs. within the supraorbital canal. This series includes the lacrimal des- The infraorbitals. cribed above, and another group of bones which extend from the Sk 2 ee ot YLitecit egoleveb si ened Intact ef ast ate, , | eyed coiiw eects yd Betotet need epnie pat i ah hatin vi ' ,emed oft Bar [aise eft to ano tials Le ois oid : aattectniene es Nie Z efteteqee Yfesitae servit te et Laney eAd » . oe tieso 2 a «+ G2" ) dostec Di -lstuex¥ eit to ¢xeq alam edb ‘aces a gt selitss hetsmer a , Barer bes a =prvedto bata. : ° eo BitactDiees steiecee ae heteoa Hood eved epent ; { pepe Bam, Gertiee ere eteceiet oft te eecot fegmert edt Roped, — wan yoeT .ameeti ev id oamnee Syoxdtt mort gubeirs exerts ] fateeini ae x1ot yen yest to tees rsonige le tase biloe.s: erode « eiecintireta: ylieran yedt yltetvotsts: oon Latnezo ost. : <: Mort Sevateqee ow bee ,sbiomitetoe edd fas ebfemiteaiqgas uitve ip ial dose doidw snotos ephind exveit evitoansite & ed osxagsdanaial Wedd ylreltets .fetoortt edt witae!ot shaadi Tasso tet tbtenarn Shlous(G odd at tod .efstolted ads gid im of s2 g§Dx0tat eiLamen ; esoiivpelliauso pietoseb a2. TReaage rom exe) eketennag odd —e720% inerues sl atent? ~( leliactossaetiae nat agviw. otettpitregak | | bos sivtivimA al bos ,fened edi So. S0eo mebeeteee, abe: sgowted often p al uot solvedaa ae ch dtodd? debhetoasade edt to. wet age ; ; lotadcactidr® ett qaiveve efetacout eat Liew | vil ‘[leutetal tteod ,tidto afd to Difessede wt eomod ” cute xpi . cboscowy set aol teelSlese ecedw smzot esodt cceasoy edt tet eleteo Bas sniaetot ntatsoo [Jnompgede ott of Chistes eff to demand | i odd of baw Deed edd te eeatrae Lengeh | -leceo (atidveswqys edd aldtiw oti of ¥ s6buioa!l aelvél alee elas ideoanty! ext 7 bpetze doldw seacd be qabte vottons.bas , fy My oO a . L210 posterior margin of the lacrimal below the eye, so that the most postero-dorsal bone of the series, the postfrontal, is attached to the frontal ridge, posterior to and above the eye (fig.i5 ). The whole series is maded up of three suborbitals, two postorbital@ and the postfrontal. These bones enclose the infraorbital or suborbital lateral line canal and are developed primarily for its protection. None of the bones unites by suture to its neighbors, but connexion is effected by ligamentous tissue and the fascia enveloping the muscles of this region. The three suborbitals are the most slender and reed-like of the entire series. They lie deeply embedded in the connective tis+4 Sue anterior and posterior to the eatethmoid process, two being anterior to the process and the third just behind it. The first is the smallest of the trio and the second is next in size. Both of these have practically the same diameter as the enclosed later- || al line canal. None of the suborbitals are sculptured. The | third suborbital lies below the eye and is nearer to the cutis than the other two. It lies above the fascia of the anterior fib-| res of the adductor mandibularis muscle. | The two postorbitals are broader than any of the suborbitals, The first curves around the posterior margin of the eye and is attached superiorly to the inferior end of the second postorbital. | The latter is the largest and longest bone of the series and is slightly curved dorsally toward the anterior part of the orbit. Ridges run on the anterior surface of the bone parallel to the course of the enclosed canal. Both postorbitals are firmly embed- | ded in the fascia of the adductor mandibularis and the dilitator operculi muscles, some of their fibres having their ortgin along ao} fs Besloatte at Lstaotticoy edt petted) — ap.sid) exe ert evods tax af wit any ey ei es ti ee — oO 5; s bs yn i ; wis” stidtosvecg owe ,xiaticrodre eetdd Te aw Stoetat ett eeelLene tened seat” To fe? eet. vot yviktecnize toqioleved ews bas Lene> eens jetodfgisn ev! 6¢ otusive W sevine senod ott to. = ‘Steeet oi? fas enecti Auotnomayht td berestte a .woiget widt to. eetpeum « B6 edil-boor bas rshiteic ¢eom edd: ote elatkésedme: conte. mit evtvoennoo oft af heibedme wiqeod ett ‘peal dookene 4 entod owt ,ssecota biomitedoe end et tolted 80g dass exit ac? .d2 Dutded tent. patad eae bas feesorg eiit on Beasoh .sete ni txen at broses oie lead arnt: ent 20 faettane od etovet feeclone edt cea teteneif ecee ath vilsottoang oved; 9 of? .Bexotoivos ats sledidtrodue ene to enol» anne stico odd of rerspo Of Bas eye edt biog! sels te havedwe. 5 edit xcliethe est to sisset odd -evuds cake were redzo eddy a .sloacn etre lod bbaaa rovonbbs exit) % ; . aeles td vod ce to [We mea? tehsead eds a fet tdroteoq: owe en oe i ; | ~| % 2 wi Vu , + Vitae 2a oh af’ = , by = “co aigtom totietecq ett) Bagove Bevis ¢ sLet toda bnocee eft to baé totvetet oat 62 Ulxot tuquet te ft Baer sets of? To ened Fe@nhol bas faveatal exit ab nessas ; stidxo eft to toes volvetdam etd Seawbd elleazed bere ytd efit of (elleter enot etd lo eentine 1ot tote ei \a0) ae ‘ orit ote eletidtesseq Ao08 Lame mma wee (ib of? bae elrealedlbanam s0teebbe eaee m4 me Poy a 7 the ventral surface of these bones. The most dorsal and posterior bone, the smallesttof the series, is the postfromtal. It lies dorsal to the superior end of the second postorbital, and like it, is embedded in the muscle fascia. This bone is not as flat as the others, the posterior margin being grooved, the margin of the groove projecting dorsal-| ly. The posterior end of the suborbital canal, which passes thr through the other bones of the chain lies within this groove. The anterior face of the bone is sculptured. As remarked above, the postfrontal is connected with the frontal by ligamentous tissue. The principal morphological feature of this series of bones is their relation to the suborbital lateral line canal. From the lacrimal bone this canal extends through the infraorbital chain into the frontal. As it passes from one bone to the other it lies within the connective tissue which joins the two bones, and at these points between the bones, from lacrimal to frontal, a dermal tubule extends from the main canal to the surface of the integument where it opens by a Single pore. There are five of these dermal tubules and pores between the posterior end of the lacrimal and the junction of the suborbital canal with the supra-| orbital in the frontal bone. There is no tubule between the lacrimal and the first suborbital nor between the postfrontal andj the frontal. There is a sense organ in each bone of the series (ites in )% The development of the bones has been studied by Klaatsch ('95) and Schleip ('03). The former claims that all the bones develop. from osteoblasts which proliferate below each sense a, ea ps dencd ene } os iuttagi fuses ed? shod ToirtsetEecg baie te + ecee ect of Teereh sekl 71 pir oe is phos ut a! bebhedme et . TF GHlt mnie , Lotiddotecd Bao | ~étredaee ait .areditoe att Ba parr os vom al emod eitt sisetch anid ost oo: svOORS eid To ointam eng -bevects gated a reli. | Si? senteq solide ,[enao EeviGrvodic eng to bre tolveteog ex?’ od ora aldt wtitiw cell ated edt Sepied & ened sit [re a antetuiaa sf. .s giefnst. .evecaldosteo enre ogod mont an Reg ees: ees - eurt tett esintad een eLflne reat st at: 08 a a eet evin dotcw esott of siexsanoe seve eye steno | @nod famreh iirc igs ,btogiiteatque ._ feterort, odd an pened i ie 62 cised eono! ed? aumeeme to Sono Lewed odd nT bsod | “ Selanec eAt enale mm £¢ edivimh fas betwee eva tiesto baa a Befveoo sit od seofo ets Hobie, Ml lin een saipdes. mi . mort Becoloved pi exed eX? To é@en emmy /fiaw ane To molgen e¢ afbeomt oft cb abooet edt te be tenses". vitob oat exardt ot efds sede J pf evad. I ted ; sRemed *% wef teettiees. ade gaeet olde asesidoeseo + sTShilo of? ai yrav sedod ‘sgentt te ox tt. brs: rosaue, ed? ison | age aon ,itleeq ‘tistit Ind .sieoe tet. ae ebtonss (tos inet | | iti [etevel Loti dsoduea ede of oo itefex tredt bus oye. aaa’ oo jlo otvese svitsrsqsoe rebie’ edt > .tastempe . -o ,siievidtoatini eft es Tivnagos tt Lad etietidzodss: odd smut cei edd se getzes eft Fé ened seitetns eft tto | : . soe eo L am eit-et mol¢éatet hap sete, efiote. tnyooon ssedt mozt xecots tuenmete) ania lstnee, me =) La =: v = ir] boon « sew laneo Istidvoedpe ont ot senod esed? t | | redeloans aif -5000T, JosveRt ib edd of pened ent get ' | sede ') ah J seer todd seq beosed) ehregnd etd? ait be S226 tad enti ‘ wetves edt @f gened aie chant (ee!) tems | wom? te yirte bolhudged » adam son) eede ha bs la amit) % TO epvenoo on? vOtT sonmed) doed® ab serog ets erent} 72 tet0r of ote evecs eeeiivaes mi ae ae: lacs ee — 123 the passage of such tubules because these leave the canals be- tween the bones issuing through the connective tissue in this regio jon. Collinge ('95) has given a partial description of the rela- tions of the suborbital lateral line canal to the infraorbital bones in Amiurus catus, and figures no tubules between the lacri- mal bone and the junction of this canal with the supraorbital. Gegnbaur ('78) recognized seven elements in the infraorbital chain| of Alepocephalus rostratus, the posterior bones being situated in the muscle fascia on the dorsal surface of the cheek muscles. a dermal tubule passed to the exterior between each bone and in the first of the series, which is comparable to the main body of the lacrimal of Amiurus there were a number of tubules as in the same bone in Amia. Allis ('98) called the last bone of the infraorbital series in Amia, the postfrontal, and justifies himself in so doing, by stating that the postfrontal never fuses with the underlying postorbital perichondrial ossification and always contains a part of the suborbital canal. He states that in some members of the in : Characifae, and Cyprinidae, and in Scomber, in which the dilitator)/ operculi muscle lies on the dorsal surface of the cranium, this postfrontal lies above the muscle. The postfrontal of Amiurus fulfills all of these requirements and hence corresponds to the same bone in the groups mentioned. Aecording to this view the infraorbital chain of bones is comparable to the orbital ring of the Stegocephalans and Reptiles, in which there is usually a large lacrimal anterior to the eye, a zygomatic below the eye, followed by a postorbital, above which is a postfrontal. The fact that although the zygomatic bone is -sd. efanso 61d erect onsite ailésanlt 26% slit ai evetit svitoenmon ont dauneiee aa an | j-siex ait to meitgiroseh Leivgag s sevig oui OO” | tag ’ a m mse -Ilyoalt att neewted sefiviut o8 Sé6y9Rit bas sei a -[etidvostass edt si be iatao eidy Xp sat oscar ent | Misdc fetidqoettat edt at pinsiele Neves beg tegovet (ors ostamic sauied seret tatreteoy elt jeevguimon matadas -oefovum deedo eit to sostvne [eetdh off Be phuesh nSiain atti ul Bas encod dees apewted toitetiny edé oF beneaq sindut x rhod atsm ent el sidarsaseo et doiw ,eolree ode to. tomy | . s selfdn! Yo T8dmia 4S otenw ove dy Serr bok to, amtioet et | ohms at onod oneg x f@sives Ietidicertmd edt to enod taal ede hellen (8@') elltA ci .golod on nt tioemtd settivens), tas), fadeeriiees, ond a oh Uxitebusr et d¢lw wanct teven Ledponteaiba oft sans sattata: eniast eyewin Sas seltaeoitieao Latubinodolgan, Letidsoteog f eft to exedmas omon ot ¢add setuta oh) temas sithiane odd te soteciiib ed? dobdw ol. ,sedmoe® ai bes ,esbhateau= Bea cotede ulagvo ad? to sostare Lneveb edt ao cobt ehenmm tinoteao. | | | teu - {sicotiveqq eif elem eddwvede wekt Ladaostteed | | cfoocketioo otsed bane atacneeinpe? peedd Re Rie SLLiiens -bono lines sasorg ad? a ened | ; | ions (s¢lévosttst ed welw bate? eativengs.) jocu usiedgeoopet’ eft to gente Ledidse, odd ot eldarsac od ¢ toltetan [anitoss egrel » viLaven et iinet idi ofs ,Levidtotecq so yd bewelloh jewe edt woled, ott rod oliamcexe oft tinmodt te tote tos em shade stiducatiai eft ot feces @nil ievetat,, 114 a member of the maxillary series, it never bears teeth lends some support to the assumption that it is a lateral line bone rather than a dentary. Most older authors homologized this ring of the fishes on purely thpographical relationships, to the jugal arch of the Reptiles, and Bojanus (1818) called them the ossa ey Gaupp ('06) makes no statement concerning this homology. Cuvier first applied the name postfrontal in the fishes to that bone which is today recognized as the sphenotic, because he thought it was the homologue of the postfrontal of the Reptiles. According to Allis ('98), the lacrimal of Amia is the homolj ogue of the first suborbital of Amiurus. He regarded the adnasal of Amiurus as described by MeMurrich (lacrimal, Auct.) as the homologue of the antorbital of Amia, justifying his statement by saying that Collinge says that many authors call the bone by that name. Since this bone in Amiurus contains the anterior end of the suborbital lateral line canal, I have called it the lacri- mal, and it is possible that the long anterior lateral process may be the homologue of the antorbital of Amia. Merely because there are six infraorbitals in Amiurus and Amia, counting the lac- | rimal in the latter, but not in the former, it does not follow i that the members of the series are numerically homologous from the anterior to the posterior end. The criterion for homology rests upon the relation of the bone to the nasal epasule and the part of the lateral line that it contains. The vomer. This bone,broad, flat, and unpaired, lies near the anterior end of the ventral surface of the cranium. It is entirely superficial to the bones which invest the chondrocran-| ium in this region and is covered by the skin of the roof @& the nes OREM Lat 2s ; ait os | 7s : - 7 Ay : ; emoe ebriol Ateet etsed’ xeven th salve Bedtvet ecod ents fatovel ee ef wt tedd 1 hee “gps et? to guilt etsd bevlsoLomed wae dene T0DE8 | ba a, . S238 Jegui edt of eqlitesattaies Lpokdgi .: of -Stiagel, saeo odd meds Sellae (@f6[) eansheg, fone Teivad .eRatomed abdu Biharesios trenedete. on vote f 90! etd god? of sedeart add. gi Larne tttege oman eat oetfere. Sen he ry f 3! tsigsodt of envaned jotganedge ond a8 Beategocor yabot. + sa llvwer. ec Sy ‘toe futnoitéaeg ods ap. =e * § Foaos edt «i aims to Lemivens edi fee") enlia oF BaLbTopOA, bs . Secombe oft Debtexet of <-prstntms ho fotiérxedes trees 0,0 | odd om (.dows ,lamtioal) dAolesiict yt, Beditopes, ga. | trameteta etd tivact ,sima to Istiduptms edt, 20 enaosen ¢ s#od ot [leo atodtrs, yrem vedd aee antler Stadt astyae ¥ fF Qe¢ weitesce aft acietaon emitin at end aids epde +2 ivodL eit *2 Balfeo evad I ,famso embh Seaital saghérodse. ¢ eesvom Lerotal soltevus smed. ett. dade, eldteacq at th & le i ylere .les to fet ifrotre edt te, eppeieses age oe = e: ; co fins bee euetehad ot ¢ Latidzoettarh xe ers # 4 | hi ,semx02 ont at ton. ded xettel edt sb ast citemun exe estzee edt. fo eredmem odd izo ofl bo tolt0eteog add of ratsetna edt } we eoan eit of enéd ed? Yo nobgatan edd noqu t a ri { -sulstmoo ¢ teit spb. fetetal exe to ds A ie A at oe y * os = ces , : otloss bon tel ,beotd, ened Of6%) suemae att ems \< vlinutt otf Yo ecsicue Spadsey ef? Beams apened Dale op Wtor. «4 10 alte edd RO Seseebe al AP SEA: ® ; ie 7 agrietthaude ost deewnt Holde sekne am ie te 15 mouth (fig.¢6 ). As MeMurrich ('84) said, the bone is nail-shapea| the head of the nail is represented by the broad anterior portion and the shaft by the posterior spicules. It lacks tha anterior extension common to the vomer of most teleosts, and is limited in front by the supraethmoid. The serrate line of interdigitation between these two bones extends as far laterally on each side as the ventral end of the supraethmoid-ectethmoid interdigitation. The vomer is here separated from the margin of the descending ect-| ethmoid by a cartilaginous plate which is continuous with the palatine articular surface. Postero-laterally each side of the vomer interdigitates with the anterior edge of the ventral portion of the ectethmoids. Internal to these edges the several spicules mentioned above, extend posteriorly in a series of grooves on the ventral face of the parasphenoid. The bone does not articulate with the premaxillaries and is firmly united with the parasphenoid}) The ventral ossification of the supraethmoid extends beneath it, separating the anterior part from the chondrocranium, while the anterior end of the parasphenoid cuts it off behind from the orbit+ osphenoid (fig. 7 ). The bone itself is very thin and some of the fascia for muscle:fibres of the ectopterygoid muscle are attached to the postero-dorsal margins. It has no teeth and none are developed in the roof of the mouth below it. The development of the bone has been described earlier in the paper. Since Cuvier compared this bone in the fishes to the vomer of man, it has borne this name although there have seen been writ ten many arguments for and against this view which I will not attempt to discuss here. As it is.one of the most evident bones on the anterior ventral surface of the skull in all teleosts, ‘er. a a A gede-ften et smo eee Sieh (ee) se “eotvie¢ tol ins Boot’ end ¥ hetn totrotm gtd eiosl st -wolooire +0 £2 st) i ih hevieti ef bia ,stedetatd epee to r0atieae acitatiatireten! to exil eteprec sat «bE @n ebie ddee oc ylleretal “at es oiret ge ‘aos ii .Hetigvlathretnl hrondtetse-blondtestgae wit egos pniftievceS oie Te oat det eit nox het srg 08 oved at 16s att dtiw aversiteds 6: Golt® eteiy west ti # an? Yo obie dose Ylleredsal-S7esget .eoattse talroht Molicon Lariaer eft to eshe toltetas eng ne iw savin seinetee Iasovee sid vgendbe eseti of Lagvegan’ | -ebomiite ed! ao sevotrg Te seiwe & al thrown innit: Pete f evelveitte ton keok exod off .bronsdeeetaq edt 2h oh $ Pe icnodceatey eit Attw beview ¢tlent? #2, 508 preamble, tl dteetet einetxs blomitectqpu edt Be notdeoitreoy ead. ofidw ,nwinsreorhinots ett mts? tteg SOROCRS once af Prix ei mov’ butved Mo 2) eins Btonetigseteg Sit; To ame tod! | tO emot is nid? wre et ‘tfeett endd aff .f y alt) b . e° iJ romytetaortie ott te serditaeloesm “0% los | hes on ned FI jorom Lostob-xeteoq 60 oF bode .t! woled dtvom ed? to S664 ost an nagncevan:’ a { Raed of? al vei itee cod toneb awed mad) acted rn 0 f te ed? o¢ e@ofell oft nl ened eid? Betegees calla “ ! J 26658 ovad eteit dyvedttls emer SEER” re ‘ fan 1 i doide welv aldd Yeoleune Bae i a Ya Penrcd tenn geom n@2 te end, ade t% ed magne bane a a i ee ' i Lin Ab Ilede ed?’ covltae Leateor 116 there has been no confusion in describing its topography. In some of the lower teleosts- Scomber,Salmo, and the mail-cheeked fishes, are among the best known examples - the vomer bears teeth and it was thought by some investigators that these were an integ- ral part of the bone. Schleip ('03) has shown that in Salmo the vomer develops, as in Amiurus, from deep lying connective tissue beneath the chondrocranium and that the teeth arise indamenseneaa/ | In some of the Characinidae and Cyprinidae, the vomer is intimate- ly connected with the cartilage of the ethmoid plate. In all adult teleosts it is unpaired, although it may arise from paired parts as in Esox (Walther,'82.). In some it forms a cap on the anterior end of the ethmoid cartilage. In none of the forms des- ecribed up to this time has a condition wholly similar to that in Amiurus been found. Its limitation to the ventral surface of the cranium is not the common type of development, as there is usually} anterior or lateral processes projecting for articulation with i the cranial bones of the dorsal surface. | The orbitosphenoid. This is a large unpaired bone forming the floor and side walls of the cranium between the orbital and optic foramina (figs.6,7,16,k@ }. It is visible externally in the wall of the orbit, overlapped dorsally by the frontal and in- terdigitating anteriorly with the eectethmoid in both the upper and lower margins of the orbital foramen. This part of the bone is only a thin lamella on the cartilage which persists in the side walls of the cranium and unites with a similar lamella on the| internal surface of the cartilage in the margins of the foramen. The anterior end of the alisphenoid bone extends down in front of the optic nerve so that the orbitosphenoid is limited tr % pike mgr sapxpersas io © sf Aa ae & po in rowsedD = mel idees ond atta ei <* ett sq ei tte th He v0 textt La oF). reat salty wide Pot we ’ 2 ; : & ana sald etsit: + ome i hi ro dame salt. Si ab 1a ae noaaoe ent haha et mvt ’ a 2000% q oeaee: Pr m0 ee ets eds to nome’ iaiaers, edt res ba unex. ze ef soLitte has sce feeki(r edd LE? In the midventral to the ventro-anterior wall of the foramen. margin of the foramen it interdigitates externally with a lateral process of the parasphenoid and the line between them extends across the ventral surface of the cranium to the optic foramen of the other side. The immediate middle part of this interdigitation| is visible only upon removal of the vomer and the anterior spicules of the parasphenoid (fig. 16). The ventral anterior end of the orbitosphenoid is separated from the laterally lying ectethmoids by cartilage. The median anterior margin lies quite far posterior to the main part of the supraethmoid, but several spicules from the latter bone extend posteriorly to it along the dorsal surface of the parasphenoid (fig. 7,16 ). The interval between the main parts of the supraethmoid and the orbitosphenoid is occupied by the ethmoid cartilage. There is a notch on each side of the bone in the orbital wall, just behind the orbital foramen, for the attachment of the pterygoid muscles (fig. 20). The ventral wall of the notch cont- inues posteriorly as far as the optic foramen and forms a shelf The whole ventral surface of the supporting the optic nerve. bone is roughened by fine lines. On the median ventral part of the bone, which is closely applied to the dorsal surface of the parasphenoid, the lines run longitudinally, and on the lateral parts in the orbital walls, radiate from a center on each side (tte: 16 he A longitudinal section through the cranium shows the rela- | tive extent and thickness of the orbitosphenoid (fig. 7 ). The dorsal posterior surface of the bone is overlapped by the supra- sphenoid and the ventral, by the parasphenoid; suprasphenoid and et te ae i 4 ive a Lory aay h tw me it Savane! adit v6 | ferotat a dttw yLineret xe votadtgt oredat! wh pati: She t ehietxe so .dé neowted saif eit tus Bt 44 oe ae a So mewetot sitqo od? ot murinatoe eft to sent z a nie molistintiszesini stiv to dreq efbbia ve ated ot ain sf elvcige xobrevae eit hae temév eft to aeniice. 6 ate: eid to fine to} +edme fardney wit .{ 8f ster Ss shiendieta: wmifcl Bie ei! mort betarehee ona J Oltedsog tet efiep ecks cide cies tolvetes matbem oft, sk movt esinoltas LIwrever tod ,binmidcaugee edt, seceets Sortice Ceetoh ofd gnoLle tf oe yirorreteeq’ Baetxe ono fiiem efit neowhed favuetat ei? .( @£.9 watt) boned “a beignove wi Ste agiqgsetidto edd has lh chia = te fetidts edt a! emod eft to ebte soge) He! doton 6 se — ay w | dt to vnemdovtsa oft tod ,ctemarot fethdce one baided + ‘tet (fits ; | +tuen doton eit to Llew Latdaey of? .(08 sank) Belem eel estdd rie B OO os nerierToet eitqo eff se a6'ss eis Kags edt to sue*vrve ferteaoy elotw ef? orten oitqo ener: thas mo 210 tt fasibem eff nO .saéntl egkt we bonetauer « sl ro eowite fwerdh edt ov betiags vfeeets ee dotdw ves ea? | baa ,vllentbetignol aux genhl @ay {Rtome: ehie rione Mo tetrnoo a mort otaetiss elise fedidro ‘edt ns ; Py | 7 8 Ae 3] a r %* el cr si, “£1067 ef 7 * mex fa @pinetso off dapout? noltvoer Lomtar? bauol & nf ast. y ol?) Blhenecdueot!dto ef2 Yo ceadtotitt bas tot ‘eeu lh -etqus o69 Qi bouqaiqeve tl encod ef? “te ooetaie 2 tw ere - | - bos Atecesquerque ;btomedgerisg oft yd Kort tt Bis - 7 A HS — = SSS aa a a as : = ’ 118 parasphenoid bones fusing at the posterior margin of the bone. Anteriorly the orbitosphenoid thins out and passes gradually into the cartilage of the interhasal septum. The middle part of the bone has entirely ossified, but the persistence of cartilage be- neath the external lamellae of the lateral parts of the bone shows! that ossification ossification does not extend uniformly through all its parts. The frontal overlaps the dorsal margin of the bone in the cavum wall and in line with the epiphysial bar region the alisphenoid and orbitospehnoid meet above the optic foramen. Considerable carthlage remains in both of these bones in this re- gion, but between this point and the anterior end, the part of the orbitosphenoid which forms the wall of the cavum is well oss- ified. Below the optic foramina the orbitosphenoid-suprasphenoid | interdigitation continues from one side to the other within the cavum, marking the posterior limit of the orbitosphenoid as a lining bone of the cavum cranii. (fig. 7 i The developmental relations of the orbitosphenoid have been given in the 32 mm stage (p. ). The perichondrial ossifi- cations in the wall of the cranium which now form an integral part of the bone were just beginning at that stage. From the description immediately above, it is evident that there is consid-| erable cartilage yet remaining within these osseous lamellae. The ledge on the external surface of the bone between the orbital and optic foramina is developed from connective tissue surrounding} the ventral end of the alisphenoid cartilage and the trabecula ecranif, and is intimately connected with the perichéndrial ossifi- eations of these cartilages (fig. 3 ). The stout median part of the bone is developed from perichondrial ossifications which have | re TEN dae v el Vda ie Me AE ‘arsed ent Pt as. “meosieia Pak CE ene GAPE, Rae: EMF peas. pi edt to trag efbhin ed? agaqer (eset -e6 eyalit+ae to sonetelexeq eft’ tud , is fe emcd ag? to et sgt), obemegonmmveo pote ney! : . ye 7 dro ef to anetislex soteeeretemnhealin doite, aff .{ -¢) eaete mo Sb) 8 ven doliw mtnero edt to iisw babe qath dadt te gotamtaeds saxt etew PN lfintvoltte edd vet Seyoots eivhaat ve0d? of bedoadds oi gamit ealieler ed? ,;@6a 66 tehi tae eA ene. 3 datwe swelenesriese ocean a hi , Li ¢ te) 3 | 157 Salmo,the bone is continuous posteriorly with the bones of the pterygoid arch and bears teeth on its ventral surface. In the Characinidae, the palatine bone has varying sizes and shapes, but it is developed on cartilage continuous posteriorly with the cart ilage within the pterygoid bones. In Erithrinus, the maxillary articulates with the palatine in the same manner as in Amiurus, but the palatine does not extend as far forward. In Scomber (Allis, '@3), the palatine is fused with the anterior bone of the pterygoid series and bears teeth. The ectopterygoid. This bone develops by the ossifica- tion of a sheet of connective tissue ventral to the valatine and connected with it by connective tissue (fig. 15). The poster- ior margin interdigitates with the anterior margin of the large metapterygoid. MceMurrich ('84) described this bone as "number four’ and stated that it could not be homologized with a ptery- goid bone because it was developed from membrane. Schleip ('03) found that it developed from membrane in Salmo and yet maintains that it is the homologue of the ectopterygoid of other teleosts and that it is separated from the pterygoid cartilage by connect- ive tissue. The bone is very small, quadrate in outline, with delicate sculptured radiating lines. In Salmo it is longer and thinner than in Amiurus and has more of the character of the cor- responding bone in Amia (Van Wijhe,'82), the Characinidae and the Cyprinidae. There is no enotpterygoid in Amiurus. The metapterygoid. This large bone is developed around the pterygoid part of the pterygoquadrate cartilage. It is quadrangular in outline and interdigitates anteriorly with the ectopterygoid, posteriorly with the hyomandibular and ventrally ah Anaghy ru ’ , a aay ~ on Ts a ee aes ; wy / be comoded? dt iw yivolddtece™ ‘on eet i eit al .apetae fertaev ethan steed | + bacd .eecado bon sesis geiguey eat enod onthe Forso edt Wtiw (ine tread wag evotmtinon ogelittae vteiitzar ect ,2caiidt Ih ah \sesded) dtoayseta, a ,errvied of os tennant emse eft at ontte Laqvadt Tedeovt wl = .drewsst te% an buetxe, ‘tom woah en 62 %6 Sade tOlsctan eHt Maw Ketut of enbtaleg, old yt pe ersed jeans -sotileso ef? yd sqeoteveh ened aid? ©. Bzenymerg got niteian edt of Ieatuer ebemet avitvoennes to teoa heptane eft (20 spt) erate avadecummeueeyed vith b 4 j 4 J L oa "7 + erie 4 ") @giet ona tdmon woYt Seatfeved eamahe ome i us omiot a2 enezdmem aost boqoLoved stogas2b ies i testo Yo Btowgreindtoe edt to ecgoLomod., ext isk this i a ee 7; esmind % \Lidveo biegy tq edd wot Deteraqed @hogeitadé = { ; rit vie ai oletbeno ., hase geevesh onod: oat parents os . tonaol ai ¢2 omfat at ceents ‘patanshes pq TetaaEe | | | bis owbdntowns> way), (Ah emt ae ae) tm, ahy ariutsh ob Bhogetesadonered bh | soqeleveb «1 ccod seyret ekdT)).Rioayaam soyalitiar etexbanpopymetar edt ie o vite ylteltotas sete? igibretal: baa, | (Clextoev base aelodlbasnoed ont ditw x | ———— | 158 with the quadrate (fig. 15). No cartilage persists in any of the visible parts of the bone. Medially it is attached to the lateral surface of the cranium by a sheet of muscular and lige- mentous tissue. A mesopterygoid occurs in most teleosts between the meta-and actopterygoids, but here the two interdigitate. In Scomber a small strip of cartilage intervenes between the meta-| pterygoid and the quadrate and a space and there is a space betweef the former and the elongate hyomandibular bone. In Salmo (Parker,'73), the bone is not nearly as great in extent, occupies a position entirely dorsal to the quadrate and is separated from the latter, as in Scomber, by cartilage. It does not interdigi- tate with, but overlaps the hyomandibular. In Megalops (Ridewood, '04), a large ectopterygoid hinders its anterior extent and it overlaps the hyomandibular vosteriorly. In Pleuronectes (Cole and Johnson,'01), it is smaller than in Amiurus and lies poster- ior and dorsal to the quadrate. The small metapterygoid of the Characinidae is separated from the ectopterygoid and quadrate by cartilage and there is also a large foramen between it and the latter. The quadrate. This bone is situated at the ventro-anterior end of the hyomandibular suspensorial apparatus (fig. 15). It is grooved on its inferior face for articulation with the mandible, is rather small, and firmly fused to the surrounding bones, al- though there is a small area between it and the hyomandibular, where the underlying persisting cartilage shows between the bones. | Its posterior face interdigitates with the preopercular bone. MeMurrich ('84) states that the cartilage mentioned as occurring between the bones is the symplectic and that in perfectly dried : cdiostac a Ati ass "ie Soe fl es dks poniian als a edi ot bedesita- at ¢: yllarbeu ors) -eg!l bue talspesa to deetle & vd antec 2y, Ue ; yr abe ae. ‘ aaa was P-fsea oft Avewtsd ponevesd nd onaLiveas to iste ch, a .. mewied boars 2 ‘ul eisdd brat, eongs 2 bag stern, ed + pith | oaod,. tmik dMbarseoys ot syaole fa; oss dig | teows aa’ Xi ‘ves tol et. iad ont, (8 ~~ (8 etat ting. ese e ieerab wheshiae uy: ; tl .opepittayp w ,tedmona ab en edt. -1 Ludi boasout, og eqelzrevo tm. i ~—_ at atl grofintt hlowgxetqgetes ¢ £5 (eon. motels al eltol <9t2-00 weal va at see vedfeme) 2. 2d it eso in oT, .everbenc ed? 62) mie goton ent moet shasta 2 nomctot esrel @ dele al exod? box onal it 7 . es mperved atecosfes teom oi entson bioayterte sHietieibxaial om eit stot tud ..e8 £ ALO’ l roshisgste xnludsbanmgpieodey te incilze veo soa codueed: thao 6 | “ny caf’ of ead gies) baw «thane. wedton: Y fun dd oowhes, sete Am geet ip: a ial : i’ ia "oe gwoit p stae yuseot vieqeety off délw ceded ind ored Seaclines eyelittep git dmfy | ) vitewzeg ml ged’ bam olepesgamm ied Lev | 159 skulls there is an interspace between the hyomandibular due to the ahsence of cartilage. The hyomandibular. This large bone connects the quadrate with the cranium. It is immovably fused with the latter and if one moves, both must. A process of the bone projects from the anterior edge to the lateral surfaceo of the alisphenoid which is hollowed out for its reception. Posterior and dorsal to this point of contact the hyomandibular articulates with the side of the cranium in a groove which has been described in connexion with the Ssphanotic and squamoso-pterotie bones. There are several ridges on the lateral surface of the bone along which the adductor muscles are attached (fig. 15). Just above its interdigitation with the preopercular, is a foramen for the pssage of the ramus hyomandibularis facialis. The knob for the articulation of the overculum has ossified and is overlapped by the ventral surface i of this bone, which is hollowed out as a socket for movement on the knob. In Salmo (Parker,'73), the hyomandibular does not have the| anterior and ventral extent that it has in Amiurus and it is iso- | lated from the surrounding bones by wauwiiaees Parker does not figure the foramen for the hyomandibularis nerve, but from gaupp’s| figure ('06) of the foramen in the younger stage of Salmo, it is evident that the nerve passes farther forward than in Amiurus. In the Albulidae and Mormyridae, and other lower teleosts, the hyomandibular does not have so great an anterior, posterior, or ventral extent as bunkeiteie: and cetniiies a small symplectic ele- ment comes between it and the quadrate. The preopercular does not articulate with the hyomandibular as elosely as in Amiurus. In ie erat an ‘en + ceewtod ¢ i “ae 7 an ? ay): iL satal sidt . | 7 in v viol ' 4 ou ue 4 a | i... .SGled elsore”g cHonomampe t bite ‘” Aue f \ : v . a ote sft weed be saiod en? te BOs tava fen + BA i ee i nM 5 ' I j : fF eve ; a Gi Oe soit) Pa: pS Bo. oF Sa i ? Lis >. mi / . \ : r 4 ° ete itor a mt ' i. tpt geitg “ “8 5 a v ‘ . of cite oat tot dom edt ° et token nee Si bane FS ih ay Ot c fegonitevo 6k Bre Seiti avn ha: merc of ae deta | oO he - nod anit 3 fa a Leo l hoyd end, x Ce oe -ofetbese end: he . é : z 4 «a ‘ } fod I 5 ie or i 160 all of the teleosts the hyomandibular has a knob on its posterior | edge for the articulation of the operculum; in some of the Chera- | cinidae cartilage persists at this point. The dentary. The teeth which are borne on the lower jaw are attached to the medial dorsal surface of this bone, from the symphysis as far back as the dentary-articulare interdigitation. The bone retains the shape and relations which it had in the younger stages. It tapers anteriorly where it meets the fellow of the opposite side and is deeper posteriorly (fig. 15). The inner surface of the bone is hollow for the reception of the ant- erior end of Meckel's cartilage. The ventro-anterior surface if perforated by a series of six pores for the passage of tubules of the enclosed mandibular lateral line canal (fig. 11). The canal issues from the mandible through the more posterior pore and enters the connective tissue surrounding the quadrate and . thence passes into the preopercular. I agree with McMurrich that the dentary is a mixed bone and is the result in part of the oss- ification of a portion of Meckel's cartilage. The developmental stages show that the bone . at first arises entirely from the connective tissue membrane around the cartilage fused witha lateral line ossification, later part of Meckel's cartilage ossi- fies and fuses with it (fig. 24). The articulare. This is a triangular bone at the posterior end of the mandible and is grooved on its posterior face for articulation with the quadrate (fig. 15). It does not contadn a lateral line element. The internal dorsal surface is flat and gives attachment to the muscles which move the lower jaw. Con- siderable cartilage persists between the outer and inner lamellae. f atben ont a, wei ap ro sal one s my st ontater a steed vl +s 80Qs ut ots ebie ae a's ‘a > 7 al exit ‘to outs bie tented Mig. me ‘fettook ‘a, 44 hi watedt Bienen: besoforte edt D ; ; al Ak n\ oft oe ovaes eag tenet ‘Ba soltvtomr & teche ted tae prod elt dank? wore sonar: ev 2 s a tdmem street t evidec ’ vi ate OD ue T P ; Le 7 . ® os — obttuse ents: le tedad nes. t Aviw poset baw a pert i ae ’ ari ve f @nome ppitta: 100 ahdee | 161 The bone bears no teeth and interdigitates anteriorly with the dentary, which also extends posteriorly in a groove on its ventral surface. The preopercular. The manibular-opercular lateral line Ganal enters this bone from the connective tissue surrounding the posterior ventral end of the quadrate (figs. 11,15). The bone is fuged solidly tothe quadrate ventrally, and to the hyomandibular dorsally. A small process projects down behind the guadrate and into this part the opercular canal passes. The posterior edge is ridged and projects above the more posterior lying operculum. The dorsal end of the bone extends for a short distance behind the hyomandibular. There is a small foramen in the middle part of the bone for passage of a branch of the hyomandibularis facial- is as it descends after passing through the hyomandibular. The subtemporals. These are two small bones lying dorsal to the preopercular and above the posterior margin of the hyo- mandibular (figs. 11,15). They contain the dorsal end of the opercular lateral line canal which passes through them into the Squamosal. They are very thin and the canal in passing through them, lies in a groove rather than in a tube, the ventral and lateral walls of which are thicker than the very thin roof. Only one such bone is found in this region of Salmo having the same relations to the lateral line canal and the squamosal. Parker ('72) called it the supratemporal, but the eet heat of the Stegocephalans always lies medial to the squamosal so that this bone could not be its homologue. Ridewood{'04) suggests the lovm eheniet here and says that the real supratemporal of Salmo between the back of the squamosal and the post-temporal was ower aeDnord Lemp : ULE aes : , s - : ; : -Cosmic Ienso talvoxeqo edd @tsa Bhs en, a ; } mur l f et sat evods footy : oe ’ a, iar. ¢ , cihretxe epod edd 3 oi: out?) - wa LET P , ities 7 eo elt catpedit Mets o* 34 0 f ; P rir: Te exL wae itaeoen Of pr : eitex svootn s Roll meat : : de » Sie m™ H , = . 8 folie to ef 4: fes 036 | Tae : > i : ? al hoyvot el 8 od dos exo ; | : Ai a { ie egal edt. <8 noi ei 4 1 ‘ t. 4 icy ' 1 betige 8 1) oxrognet atta bi ‘ amoLadgesoyer ' phe bis 6. @ a Lomond ns 00, biuee Y YY 7 “¢ edt dade nye, an “ah botqok hs Df Lat ROMA p he ott a0 rt set ait 2 v ’ Ui “? 162 looked by Parker, but it is really larger than the subtemporal. Sagemehl ('85) states that these bones are present in many of the Siluroids. The opercular apparatus. This consists of three bones; a large dorsal operculum and two smaller ventral bones, the inter- and suboperculum, (fig. 15). The operculum spreads out posterior-| ly in a wide arch and articulates anteriorly with the hyomandibu- | lar knob. It is heavily sculptured on its extermal surface, tap- | ers ventraily and at its inferior apex the short quadrangular interoperculum is attached by ligamentous tissue and interpolated between it and the posterior end of the articulare. The suboper- | culum is smaller and lies medial to the interoperculun. Summary. 1. The chondrocranium of Amiurus is platybasic. 2. In the chondrocranium of the 10 mm Amiurus there is no internasal septum; the epiphysial bar is the only part of the n chondrocranium dorsal to the brain and divide the opveing in the roof of the vrimitive skull into an anterior and a vosterior fontanelle. 3. The olfactory foremen lies in a sagittal plane and is very large in comparison with the olfactory tract. A solum nasi is present. The ectethmoid process, a short transverse projection between the nasal fossa and the orbit, is perforated by the ophthalmicus superficialis trigemini. An orbital foramen is present posterior to the ectethmoid process. 4. Trabecular and alisvhenoid cartilages form the margins ete (ae" ereblow ui lte aoe t 7 . + OD) STShggs Meise eco edt i nt —_ ye > hi ¢ Be marty om p oqo Ia Lae < ORT Ss nae |! mst Biss tec ate HG b«} « , Lim i J becosatis ot eu ody ae : 7 7 ‘etrcortbnodo an 5 eT’, y logtoothnode ett at a ) 4 a] oe: 4 ef? ;:owiqes Ieeerretxt on 1 » ° ron or ' . bos ore $ of L250 b mabe [ey fooxs I ; F 7 i 4 C ey. + Pm thy! ent to & a 90 tT " 4 | | ed Lonstact °«¢ 4a , cota biomdtetes off | tneners wg 5 ant 7 @i . eeect Leann ef soowted sett c ry of t - inthsents? effete! ecm paghett ‘e rd sodnog | pba? ett 8 ong blomitevoe edt ot 201 ata <- hioneiqaile Bans * ‘f af . 169 of a large fenestra in the lateral wall of the cranium for the passage of the optic,oculomotor, trigeminal,abducens, and facialis nerves. The fenstra is closed by membrane at the 10 m stage, | except where the nerves issue. 5. The alisphenoid cartilage is the homologue of the ala magne of the mammalian chondrocranium. 6. The cavum labyrinthii opens directly into the cavum ecranii; there are three sevta semicircularia; no basicapsular fenestra is present; the glossopharyngeal and vagus nerves issue from the cranium between the otic capsule and the psrachordal plate. The otic capsules are fused posteriorly with the nnaibetteal arch; a synotic tectum is lacking in the 10 mm Amiurus. The hyomandibular articular surface lies external lies external to the lateral semicircular canal. 7. ‘The parachordal cartilages lie lateral to the inter- cranial notochord, are fused anteriorly with the trabeculae, dorso-laterally with the otic capsules, and posteriorly with the occipital arch. The notochord forms the axis of the posterior part of the solid parachordal plate. The sacculi lie in recesses | on the dorsal surface of the parachordal plate on each side of the notochord. 8. The ventral ends of the occipital arch are fused with | the parachordals posterior to the vagus foramen; the posterior end! of the arch is inserted into the anterior end of the third neural arch. The hypoglossus nerve has dorsal and ventral roots united within the vertebral canal and a single lateralis ramus issuing between the occipital arch and the anterior process of the Scaphium. The nerves posterior to the hypoglossus have the rami a ; 7 ree tat eid a be es " A: urimegt rt, hecahis tc. on ttqo ent to .sneochds , d be colo at ' atte £ ages v eseet say 7. eta rdme ' ‘ I gurvae edt i y ataes se tdt OTB et “e ) eS i 3oln edd regen er a nom | a i ait end Oe wied wirie ect mort pelveqso otto § wie fc , - ; must oot ottonys s jdore at johtxs est ers ,drodooten £ ahi nto tio ent dtiw ehiese ts al-oe 16 b = 7 . q vsrodooton ent — be tqtooo _ | as Bios se to dta@ py \ , pootuum Laprob edt so ~»* , ad 4 pettood on edd 7 4 ; ebae {[atiaev eft oe _ it of tolxedaoy « don sat edt ig odmt bet cond at de ote ea on’ ad ovens ewecorzoqyi out . ‘oo i ¢ > [ageo : ottev oxi nut Aras » " ’ 4 e i, ad Dae eit bas sore qtose « oft nos - pix ott Mtarheleys wera 164 characteristie of true spinal nerves and alternate with the neural arches. Two pairs of myotomes are present lateral to the occipital arch, but their innervation by the nerves in this snes iate region could not be clearly made out. The two pairs of myotomes following these are innervated by the second and third pairs of post-vagal nerves. | 9. The anlagen of the premexillary and maxillary bones are present in the 8 mm Amiurus. 10. The palatine cartilage is indenduaeat of the pterygo- quadrate, and the latter is fused to the hyomandibular. 11. Ossification is present in the skull of the 32 mm Amiurus. The large dorsal fontanelles of the 10 mm stage are limited to mere slits by the frontal and supraoccipital ossifica- tions; the eviphysial cartilage persists, but lies relatively further posterior; a rudimentary tegmen cranii and synotice tectum are present; a massive cartilaginous internasal septum divides the olfactory tracts; the olfactory foramina lie in a transverse plane. 12. The anlage of the supraethmoid bone has both membrane and perichondrial ossifications entering into its composition. The perichondrial ectethmoid ossification is fused with a connect-| ive tissue ossification on the lateral margin of the ectethmoid process. The foramen orbito-nasale lies relatively more posterior} than in the 10 mm stage; perichondrial ossifications appear on the| margin of the orbital foramen. 13. The fenestra hypophyseos is closed by the orbitosphen- oid, parasphenoid, suprasphenoid, and prootic ossifications. { oly BYT enn ato tm 0 ebam ylieeto ott vom bive DO Ta4 TOG ri oe Is ober re wad ' Sha hae be -Gevyrten fi 5 aasv=t a : me 8 t¢ rt \ 2) 7 - pend eT Bo eattsleg” oat *,OL) Tettse tot a ote-rbe soltapihtse va fnarob caret eff ay Teo fsle aarti rem? bsrt 2 pad Ted: cost g ‘gthevena e 18 evonrt qrodeetto eft ont ere Atle blomddet oe Loltbhrodet zeq off notte ott taBo weet t owt ‘ ome oe a-otidto aometot ef? TY. oF Liog 1S ate of oa at si A ome rot Log dso att $e ytad ry eavoqorys Bt *, bt onmeriqe is im biomes cae cg {mM 165 14. The intercranial extent of the notochord is apparently | less than in the 10 m stage, but this is due to the greater relative growth of the cartilaginous parts surrounding it. 15. The suprasphenoid bone is developed from membrane in the floor of the cranium and is not the homologue of the basisphent oid of the mammalian cranium, but is a bone peculiar to the teleosts. 16. A Squamosal ossification, developed from membrane, fuses with the pterotic ossification, as the latter has no homo- logue in the mammalian petrosal, the resulting bone of the adult cannot be a temporalis, but must be regarded as a squamoso-pterotig. 17. The spina occinitis of the supraoccipital bone arises | from membrane and is the homologue of the supraoccipital plates of the Stegocephali and probably of the interparietal element of the mammalian cranium. 18. The skull of the adult Amiurus is well ossified, although considerable cartilage persists in the ethmoid and otic regions. The adult cranium resembles, in many points, the crania of some of the Cheracinidse and Cyprinidae. ees staid tod ,emate ae ? Ly ' fonesge . - Fy ore: af 244) z orice te mst} Lemmesr <7 yi 7 . = ; *y ie hr ao lvselitsse Lssomasos 4 soitteeo ottozetq ond: f . dt ,feaorteq asiileumenm ed? at to esnoltomod ont st Hew enasdnen ort € 4 vidado do “tr Row 7 Dim Lindgooogett iit q te must nero naiiaenan ¢ eae vw SL ~ dap aLdaxebience savor tLe sivba eat! nots - rr [5 exit Ty) Ono R ‘to 7 ¢ - 166 Bibliography Agassiz and Vogt. 1842 Developement des Salmones. Albrecht, P. 1880 Ueber den Proatlas, einen zwischen dem Oaates| itale und dem Atlas der Amnioten Wirbeltiere gelegen pores und den Nervus spinalis I s.proatlanticus. Zool. Bag aa Allen, Harrison. 1882 On a revision of the ethmoid bone in the] Mammalia. Bull. Mus. Comp. Anat., 10. Allis, E.P. 1889 Anatomy and Development of the Lateral Line System in Amia calva. Journ. Morph., 2. 1897a Cranial muscles and Nerves in Amia calva. Journ. Morph., 12. 1897b The Morphology of the Petrosal Bone and of the ca Region of the Skull of Amia calva. Zool.Bull, ,| 1898 Amia and the Teleosts. Zool. Bull., 2. 1899a On Certain Homologies of the squamosal, intercalar, exoccipital and extrwascapular bones of Amis calva. Anat. “Anz. ,°16. 1899b On the morphology of certain of the bones of the cheek and snout of Amia calva. Journ. Morph., 14. 1900a The lateral sensory canals of Polypterus bicher. Anat. Anz., 17. 1900b The premaxillary and maxillary bones, and the max- illary and the mandibular breathing values of YPolynterus bichir. Anat. Anz., 18 1903 Anatomy of Scomber scomber (mackerel). Journ. Morph. ,18. 1910 The ana tony of the mail-cheeked fishes. JZollogica, Chun., 57. 1913 The homologies of the ethmoid region in Selachii. Anat. Anz., 44. Baur, G. 1896 Mr. Walter J. 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Klaatseh, H. 1895 Ueber die Bedeutung der Hautsinnesorgane fiir die Auschaltung der Skkeroblasten aus dem Ektodern. Ergangungsheft z. Bd. X. Anat. Anz. KSlliker, A.v. 1850 Die Theorie des Primordialschddels. Zeits. f. Wissens. Zool., 2. Levi, Giusenpe. 1900 Beitrage zum Studium der kntwickelung des Knorvneligen Primordialcraniums des Menschens. Arch. f. Mikros. Anat? u. Entwicklgsch., 55. Loomis, F.B. 1900 Die Anatomie und die Verwandtschaft der Ganodd und Knochen-Fische. Inaug. Diss., MUnchen. bts {iow ouplesp eb —— Y . « te lanasoolall *BQ6L ae “ee , Lhotaxc ato Loto twdis a Moeteals eth af : lagrnogieyT | he ie téa) ey Het ~ f eotcrm’! ebh th .2omtie 170 MeMurrich, J.P. 1884a On the osteology and development of Sygnathus peckianus. Quart. Journ. Mic. Sei., 23 oe The osteology of Amiurus catus. Proc. Canad. Inst. Mittenheimer, C. 1847 Die Membro Piscium Pectorali. Miller, J. 1846 Bau und Grenzen der Ganoiden. Abh. d. Berl. Akad. d. Wissensch. 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Sutton, J.B. 1884 Observations on the parasphenoid, vomer, and the palatopterygoid arcade. Proc. 2061. Soc. London. Swinnerton, H.H. 1902 A contribution to the morphology of the | Teleostean head skeleton. Quart. Journ. Micros. Sci., 45. | Terry, R.J. 1917 The primordial cranium of the cat. Journ. Morph., 29. Thyng, F.W. 1904 The squamosal bone in tetrapodous Vertebrata.|] Proc. Boston Soc. Nat. Hist., 32. Tischomiroff, A. 1885 Zur Entwickelung des Schd#dels bei den Teleostiern. Zool. Anz., 8. Traquair, R.H. 1879 ¢ On the structure and affinities of the Platysomidae. Trans. Roy. Soc. Hdinb., 29. #1871 Cranial osteology of Polypterus. Journ of Anat. and Bhysiology, 5. Veit, Otto. 1907 Ueber einige Besonderheiten am Primordial- : cranium von Lepidosteus osseous. Anat. Hefte., 33. j Vrolik, A. 1873 Studien ber die Verkn8cherung und die Knochen | des Sch¥dels der Teleostei. Niederl. Arch. Zool., l. | Wagner, R. 1843 Lehrbuch der Anatomie der Wirbelthiere. Walther, J. 1882 Die Hntwickelung der Deckknochen am Kopfskel-| ett des Hechtes, (Esox lucius). Jena. Zeits. f. Naturwiss.,| Gis ! Wijhe, J.W.van. 1882 Visceralskelett und die Nerven des Kopfes]| der Ganoiden und von Ceratodus. Niederl. Arch. f. Zool.,5. Willcox, M.A. 1899 Notes on the occipital region of the trout,| feutta fario. Zool. Bull, 4. Winslow, G.M. 1897 The chondrocranium in the Ichthyopsida. Tufts College Studies, l. Woodward, A.S. 1893 Osteology of Lepidotus and Dapedinus. Quart. Journ. Micros. Sei., 20. # Not procurable. - At yr tl . { o OG OTS Lasootet . & OBL) Eid these a ets to (fies: q = wT Peat» Pal reblons® e@al . edee ; > SeLL2W «oltet j dunt a Bok oroll . Riso ue 173 1898 Vertebrate paleontology. Cambridge. Workman, I.S. Ophthalmic and eye-muscle nerves of the cat- fish (Amiurus). Journ. Comp. Neur.,10. Wright, R.R. 1884 The nervous system and sense organs of Amiurus. Proc. Canad. Inst., 2, 1885 On the skull and auditory organ of the Siluroid, Hypothalmus. Trans. Roy. Soc. Canada, 4. Zittel, K. 1880-93 Handbuch der Paldontologie. Mtinchen. (A translation and adaptation by C.R.Eastman. London.). tefeu bas Rois ry a c. a Explamation of Figures. Plate I. Fig. 1. Model of chondrocranium, 10 mm Amiurus: lateral view, € 2/3. Fig. 2. The same; dorsal view, X°2/3. Plate II. Fig. 3. Model of chondrocranium, 32 mm Amiurus; cartilaginous parts only are represented on the left side; cartilage on right side stippled to contrast with ossifications. Dorsal view, X 1/3. Fig. 4. The same; ventral view,X 1/3. Fig. 5. Model of mandibluar and suspensorial apparatus, 32 mm Amiurus; cartilage stippled. Lateral view, X 1/3. Plate IIT. Fig. 6. Adult cranium; ventral view, X 115: Fig. 7. The same; median section and internal surface, carti- lage stippled, X 1.5. Fig. 8. Transverse section through middle part of the otic capsule and parachordal plate, 32 mm Amiurus. Camera lucida X 30. | 9, Adult cranium, posterior surface, X 1.5. Plate IV. 10. Adult cranium, dorsal view, X 1.5. 11. The same, diagram of the course of the lateral line position of pores and sense organs in relation to bones. 12. Transverse section through the posterior end of the occipital arch, 8 mm Amiurus. Camera lucida X 50. Fig. 13. Transverse section through the scaphia, 8 mm Amiurus. Camera lucida X 50. PF -O\D A£A,wolv Lavdney semen eit old tis grt to. Lebel a > - . ’ f [ « ‘ t | an aL . ¢ [qa et 64 [td 189 bs é . a s¢ ren | wry : ° f bas coits 98 methem jomes eat “tant nh 2.£ 2 Selagite og ce revenat? a . 9 ee i ‘ ~ - Y Pw 4 rf OR oA on ,etalq Lebvotosteg Bna one aqae ‘srtuev jmstaerve tisha . | 41) J * . 2 : _ e ¥ AN DA f ui ‘ss ) ° ‘ . a, |i a. ~weltyv . 5 ,wrlnavo TIsba | cif fae ‘¢ To metnslb ,emas edt : : 79 epnes ban setog to Pee ; ae 4 4 oS [ig Moiyoesk seeteve wl -ecrgliods om B ee soult no ttoee owtevansr? 175 Transverse section through the posterior end of the Fig. 14. orbital region, 8 mm Amiurus. Camera lucida X 50. PF Plate V. Fig. 15. Adult cranium; lateral view, X 1.5. Fig..16. The same; ventral view of anterior end with vomer and parasphenoid removed, X 1.5. Fig. 17. Transverse section through occipital region, 8 mm Amiurus. Camera lucida, X 50. Fig. 18. Transverse section through the ethmoid region, 8 mm Amiurus. Camera lucida, X 50. Fig. 19. Transverse section through the roof of the anterior semicircular canal, 32 mm Amiurus. Camera lucida X 50. Fig. 20. Adult cranium; lateral view, <4 1.5. Fig. 21. Transverse section through occipital arch-parachord- al fusion, 8 mm Amiurus. Camera lucida X 50. Plate VI. Fig. 22. Transverse section through the anterior end of the ethmoid region, 32 mm Amiurus. Cameras lucida X 30. Fig. 23. Transverse section through the hypoglossus foramen, 32 mm Amiurus. Camera lucida, X 30. Fig. 24. Transverse section through the lower jaw, half way between the symphysis and the articulation with the quadrate, 60 mm Amiurus. Camera lucida X 50. Fig 25. Transverse section through the same region, 3 mm Camera lucida X 50. Amiurus. Fig. 26. Transverse section through the parachordal plate ventral to the vagus foramen, 32 mm Amiurus. Camera lucida X 30. a 098 Pe eS -O.£ = evonet 8 X ,sbtoxl sa does WROreneHt jay hho ws sromad ‘ eatat pean hs eL alt toes oc ee on : , sat a ~~ oF "7 . pe rhah oe St ianeo vata oe - ad a; .c. »wotv ‘sitel smptasro stita ee 08. coe hs 4 bie D*] ¢ A 1 P Us Oo% ? 4 OoGg. | sevens | oy aS at : ee esl cel ,eotleh mm, 8 por ent I ol se ite : j | ef iqgotd? aottoes eeveveger? .,88 art peat a , reme .egtgimaA om 88 ,sodeet Bilomit : j % g ~ . ey votAd aolgoes eetevenstl .@& tt (a ' , -O68 % ,abionl atemeD .aneeimA om Sb oy ) . a e : : ot? nolvoes saresyensyT ae t .glt ‘ iveirot? mi? bas vernon as A nsowd aes . OS 2% shlioul avtem a tt owl? mottoes eatev ig 83 7 .08_X abtogl stone “Sar ti% soldoea ontey ,ceretot siraey »* ls 176 Pig. 27. Transverse section through the anterior end of the parachordal plate, 32 mm Amiurus. Camera lucida X 30. | Fig. 26; Transverse section through the parachordal plate posterior to fig. 27, 32 mm Amiurus. Camera lucida X 30. Fig. 29. Transverse section through the posterior end of the | occipital arch, 52 mm Amiurus. Camera lucida X 30. Fig. 30. Transverse section through the ethmoid region, 8 mm Amiurus. Camera lucida X 50. Fig. 32. Transverse section through the posterior end of the orbital region, 32 mm Amiurus. Camera lucida X 50. Plate VII. Fig. 33. Transverse section through the roof of the anterior | end of the otic cansule, 60 mm Amiurus. Camera lucida X 50. Fig. 34. Transverse section through the synotic tectum, 32 mm larva. Camera lucida X 50. Fig. 35. Diagram of nerve,neural arch and myotome relations of a larval Amiurus. Fig. 36. Transverse section through the anterior end of the anterior semicircular canal, 32 mm Amiurus. Camera lucida X 50. Fig. 37. Transverse section through the posterior end of the basal plate, 32 mm larva. Camera lucida X 30. Fig. 38. Transverse sectionsthrough the posterior end of the otie capsule, 32 mm Amiurus. Camera lucida X 50. Fig. 39. Transverse section through the posterior part of the ethmoid region, 32 mm Amiurus. Camera lucida X 30. : iS. Toltevis eric os ev z - esters. a Ue: ae ; 4 ' ~~. ss ,;%8 Bit ot bh elte ve ae, us oe -ertuimaéA® Ieytelt at [Ft ; q | i map ,feuno telvotiotadee to fred me es itevane tT 7 et Abbreviations. alis., alisphenoid bone alis.c., alisphenoid cartilage a.m., adductor mandibularis ant.font., anterior fontanelle ant.pro., anterior process of the scaphium art., articulare bo., basioccipital br., brain ca., foramen for internal carotid artery ca.si., canal sinus imparis csa., anterior semicircular canal esi., cavum sinus imparis esl., lateral semicircular canal esp., posterior semicircular canal dent., dentary @., eye ept., ectopterygoid ect., ectethmoid ect.pro., ectethmoid process end., endorhachis ep.b., epiphysial bar epo., epiotic eth., ethmoid plate eth.cr. ethmoid cornu ex., exoccipital f.bcr., fenestra basicranii anteriorius f.h., fenestra hypophyseos ik" tsf i ¢t brent 7 707 om, enstT aot 7 cayrotagton tae ba blomit ev: 6 , toe “rae tdowivol e) f£.mg., foramen magnum f.o.n., foramen orbito-nasale res; frontal hmd,, hyomandibula hmd.gr., hyomandibular groove hmds.VII., hyomandibularis branch of VII hy., hyoid arch hyp., hypochordal cartilage hypg-, foramen for hypoglossus nerve hypg.n., hypoglossus nerve inth., interhyal int.s., internasal septum iop., interoperculum 1., lagena la., lacrimal 1l.l.c., lateral line canal l.o., levator opereuli 1. os., lateral line ossification m., Meckel's cartilage mpt., metapterygoid mx., maxillary my.1-5.; myotomes 1-5 n.1-4., post-vagal nerves 1-4 na., nasal na.al., nasal alar cartilage na.o., nasal organ neh., notochord ne.1-3., neural arches 1-3 ~* as ors g ’ afd) pea: II. aba all ding | geitirao Iak bron oom, « ~ evran seolgcqyl tot com 7 - : alt oe y ait na , ” pissy > * of" a c Pps ti q °*S w .. SS _=s % =) —, } | ' [t¢1e0 e'fexoe ua | . eis) osytetqatem ,.van a ee Laat L?9 oce., occipital arch olf., olfactory foramen olf.1., olfactory lobe Op.-, Operculum oph.V., foramen for ophthalmicus superficialis trigemini oph.VII., foramen for ophthalmicus superficialis facialis or.f., orbital foramen os., orbitosphenoid ot.c., otic capsule pal., palatine peh., parachordal pf., vostfrontal pmx., premaxillary po., postorbital post., post.font., posterior fontaneile pa., pvterygoquadrate cartilage pre., preopercular pro., prootic ps., parasphenoid pt., post-temporal ptr., pterotic q-, quadrate r.lat.acec., ramus lateralis accessorius facialis foramen re.m. rectus eye muscle r.m., rete mirabile of the internal carotid artery r.ot.VII., ramus oticus facialis foramen r.s., recessus sacculi ’ “ tot noemsto pi nometot fet idt a 62 cuodae ote dtc re oa elveqcno oito Hee en cuteton “ ie 54 Lsbrode 218 . doe é ~ oor ‘ bioaedAqce eteq — oivoxet % ‘ a ; 4 ‘ stashany 428 " fe fiir on" sa., septum semicircularis anterius sac., sacculus sbo., suborbitals seca., scaphium se., supraethmoid sl., septum semicircularis laterale sen., solum nasi sn.l., first true spinal nerve or second post-vagal nerve sp., septum semictrcularis vosterius sph., sohenotic spoc., Spina occipitis S.-pv., saccus paravertebralis sq.-, Squamosal Sq.-ptr., squamoso-pterotic st., subtemporals tubule pore of lateral line canal Gee, tr.,trabecula cranii ue. urriculua vg., vagus nerve vis., visceral arches vo., vomer II., optic foramen V-VII,, trigemino-facial foramen IX., glossopharyngeal foramen X., vagus foramen rp i : 2 tox botmea mart , ee Leh ae ; cef rennet 2} i) an oltom 5 oni © bistiuiooco axken iie.- silatdedtevereq ofegae [eeor Bip & ; au a o Tad [een we ats stoqmedéus t og eed at iinet tides —T? : ay Lio iets i a. = 4 +. Se Oy f 2 vars ovTen BNy ae podiinatn * Nera to? ot 7o » Lost -ontmeghrt i { pemIry mas qo8e | a wal aed > ‘ae >» CQ © es VED AN N y ip 7 S Vii ye SSN TF ~ = a ne =sS u > ee Plate IV re \ q fj tia hm d sph. Ar oLVil § gypre Plate V CoO AN FR ge RG h- xud Se IIA ‘spul Y Plate VI