Select the correct match for $X$ and $Y$:

Column $X$	Column $Y$
$(1)$ Skin without scales	$(P)$ Catla
$(2)$ Placoid scales	$(Q)$ Hagfish
$(3)$ Cycloid scales	$(R)$ Chameleon
$(4)$ Epidermal scales	$(S)$ Ray-fish

Distinguish the characteristics for Chondrichthyes (Cartilaginous fishes) and Osteichthyes (Bony fishes) from the following list:
$I$ - Air bladder absent,$II$ - Operculum absent,$III$ - Cycloid or ctenoid scales,$IV$ - Placoid scales,$V$ - Ventral mouth,$VI$ - Terminal mouth,$VII$ - Internal fertilization,$VIII$ - External fertilization.
Select the correct grouping for Chondrichthyes and Osteichthyes respectively.

Metamerism is a characteristic feature of which of the following?

Select the correct option for the matching pairs:

Level of Organization	Phylum
$(1)$ Tissue level	$(a)$ Platyhelminthes
$(2)$ Organ level	$(b)$ Porifera
$(3)$ Organ system level	$(c)$ Coelenterata
$(4)$ Cellular level	$(d)$ Arthropoda

In Mollusca, excretion occurs through $......$ and in Hemichordata, it occurs through $......$.

Which of the following statements is incorrect?