OCR Text |
Show 1882.] CLASSIFICATION OF THE COMATULCE. 733 The following are cases in which Prof. Bell has wrongly applied his own method :- 1. Antedon macronema. According to Bell's formula (3 A -) this species only differs from the ten-armed Ant. rosacea (3 A--) in the cirri consisting of more than 40, instead of less than 20 joints. And yet Miiller1 says, " Aus den 5 Armstammen von 3 Radial-gliedern entwickeln sich meist 3 Arme, so dass sich ein Stamm zuerst in einen dicken und diinnen theilt, der dickere aber fiber dem zweiten Glied oder brachiale axillare sich wieder in 2 Arme theilt." The " brachiale axillare^ is what we now call the " distichal axillary ; and as it does not " present a syzygial joint," Prof. Bell's formula should be V 3 A ^ c . 2. Antedon palmata. The same formula is given for this species (3 Ap) as for Ant. carinata, which has ten undivided arms. In Ant. palmata'2, however, " Die 10 Primararme bestehen aus 2 Gliedern, das zweite axillar. Nach der Theilung wieder 2 Glieder, das zweite axillar. Entweder bleibt es dabei oder die Arme theilen sich wieder." That is to say, there are two distichals and two palmars, and sometimes even a further division, none of the axillaries being syzygies. Hence the formula should be V 3 A^ ; but this is insufficient, as it gives no information about the presence of any axillaries beyond the distichal one. Both the errors above noticed are due to the omission of the sign /J , and are possibly due to the printer. But others are of a much more serious character and require to be treated in more detail. 3. Act. alternans. For 3A'RPP"° read 3 A'DP'(P'")°- 4. Act. bennetti. For 3A'RDP5 read 3A'DPP'(P")^ 5. Act. japonica. For \/3A'R° read 3A'DPB- 6. Act. multiradiata. For 2A'RDP^ read 2A'DP(P')|? 7. Act. novce-guinece. For 1(2)A'RDP^ read l(2)A'RDPP'(P")x b. 8. Act.parvicirra. For 3 A'DP(^ read 3 A'D(P)(^- 9. Act. peroni. For 3A'RDPj read 3 A'DP(P')g- 10. Act pulchella. For (1.2)3A'| read ^/1.2.A|, and 3A<*- 11. Act. schlegeli. For 3A'RDP§ read 3A'DPP'P"g- 12. Act. typica. For lA'RD°read 1A'RD{PP'-Pv|°- The presence of R or D in a formula indicates that the radial or distichal axillary " is a syzygy ;" and this leads to confusion, for the two cases are not homologous. The radial axillary is never a syzygy in the sense that the distichal axillary is, or that the third or any following brachial may be ; i. e. it never primitively consists of two 1 Loc. cit. p. 258. 2 Oattung Comatula, p. 261. |