While is a highly regarded academic resource, there is no official, full-length PDF available for legal free download due to copyright protections held by Rastogi Publications . However, you can find legally accessible digital previews, educational excerpts, and affordable official versions through various platforms. Legitimate Ways to Access the Book
It is often easier to print only the required diagram or observation sheet for a specific practical session.
Without direct access to the specific book you're asking for, I can still give you a general overview of what an invertebrate zoology practical book might cover:
is available for online reading, though many pages are omitted for copyright protection.